‘95 OBD1 GSR. 190,000 miles BLUF: SOLVED! AFTER MUCH TROUBLESHOOTING THE TPS SENSOR IS THE FIX! Details below:

Condition: car runs perfectly at cold start a majority of the time. If I cycle the ignition key while driving a partial throttle power loss/bucking/surging condition begins. No CEL’s associated. Happens at all speeds, all gears. If more throttle is applied it will surge back into power. If heavier load is applied, no issue. No stalls. Steady idle.

This also happens if parked for a short time and restarted

Note: there was a persistent DTC 43 that triggered 4 minutes into driving/load condition like clockwork. Condition was present before maintenance and persists. This has largely gone away since the following maintenance has been carried out:

Recent MX this month:
Fuel Pump (255lph)
Fuel filter
Timing Belt (water pump, tensioner pulley/spring)
Supertech LMAs
Supertech Valve Guide Seals
Valves Adjusted into factory spec (In 0.006-7”; Ex 0.007-8”)
FITV retightened
Throttle Idle Stop bolt adjusted
VTEC Solenoid cleaned/repacked
Compression tested good
Leakdown Good
Timing set to 16° BTDC at 750rpm w/SCS connector jumpered
02 Sensor replaced. This was the part that seemed to keep the DTC43 away.
Reset ECU (battery terminal disconnect/discharge 10 seconds)

Items to left to address, let me know if one of these is a smoking gun:
exhaust leak between DC header and Test Pipe (new will be here Tuesday, this one has NO chance of aligning for a good seal)
TPS voltage test (.05V closed; 4.5V WOT) and recalibration
Fuel Pressure (have gauge that needs installed, fuel leak fiasco had me defer that till the leak was figured out). Will be looking for 39-46psi at idle, 48-55psi w/ FPR Vacuum line sealed closed.

This has been heavily searched all week. I have read where others have had a similar issue and no followup or solution is ever posted.
I have read possible failures not addressed could be:
Fuel Injector
Fuel Pressure Regulator
Ignition Coil
Cap/Plugs/Wires Rotor. These appear new and are an OE replacement Distributor. The MSD modded diizzy came in the trunk with the car and no explanations. Plugs are white, very little soot, good gap, and good tips.
Random vacuum leak (I’m doubtful here)
EGR
PCV

The crux of this whole thing is it happens when power is cycled. Imagine driving fine, cycle the key, and IMMEDIATELY the problem begins. All updates will follow this thread. Any and all suggestions greatly appreciated.

 

Since this time I have installed a fuel pressure gauge onto the fuel filter. Fuel pressure holds static at 51psi and operates at 46psi, no fluctuations.

Checked voltage at TPS. Should read 0.5V closed, I had 0.16V.
Should read 4.5V open, I had 4.6V. I decided to reclock it and now reads 0.32V closed and 5.0V open. I decided since my problem was lower rpm I would favor a closer reading at the low end.

The new test pipe has been installed and the exhaust system is now fully sealed and the 02 sensor isn’t getting any residual atmosphere readings.

I opted to replace the Main Relay because it was the next cheapest thing and is still fuel system related.

I have had exactly 1 restart issue in this time, right after I installed the relay. However, I can feel a very slight miss under load that isn’t triggering a CEL. Under WOT I don’t notice. I did have a Code 7 kick last week when I went for a 5-4-3 pass on the highway, but that has been the only indicated issue.

Next items are to replace Spark Plugs, and I am leaning towards ICM. If those don’t fix it, I’m down to cleaning and checking injectors (which I might do prior to ICM because it’s basically a cost free step and will rule it out) and then finally the ECU.

Any other inputs will be greatly appreciated.

There have been no recorded code 43s in a while, I can only surmise that the Main Relay and TPS clocking fixed this, the TPS being the first fix where the CEL didn’t trigger. Car is 98% of the way there

 

After digging through my garage stock, I found an old distributor that had a functional ICM in it. I swapped this to my current distributor and re-rechecked timing (16° BTC w/SCS connector jumpered). This did NOT fix the restart surge problem, but it did seem to help the slight miss in the top end.
While changing the distributor over I wanted to give the ECU a fresh start, so I disconnected the battery terminals and touched them together for 10 seconds to dump the fault code memory. First test drive I cycled the key and the problem returned immediately.
When I returned to my garage I wanted to try resetting the ECU again, same method as above, and when I restarted the car (warm, only 2-3 minutes had elapsed) the problem was GONE!!! I cycled the key again and the surge returned again.

This leads me to a few possible conclusions: First, I'm glad I didn't shotgun the ICM, that cost would have sucked to disclose to my lovely wife.
Second, it is electrical in nature (not fuel or metered air) and has something to do with keyed power cycling. I want to suspect the P72 ECU with the shoddy S200 equipped, wiring, or else its something in the system I haven't thought of.

I'm running out of talent troubleshooting this problem and hope one of you has a suggestion to point me at. With the exception of some gnarly wiring from the last guy and rough body repairs, this is functionally the only issue left with the vehicle. Thanks in advance.

 

Replaced TPS Sensor Today. Clocked idle to precisesly 0.50V and that resulted in WOT reading 5.0V, not the prescribed 4.5V. Since the problem happens are part throttle, I err'd on the side of idle. First startup and drive, perfect. Stopped off at the store and after restarting 10 minutes later the bog/surge returned, lightly, until about the time I cleared the parking lot, maybe a minute or two.

Cycled ignition while rolling twice before parking and NO ISSUES AT ALL!!!! I'm not totally convinced this is the full fix, but if it is solved, I will update the OP with "Solved" and the BLUF of the TPS being the final fix. Fingers crossed.

 

Have driven car around all week in varying conditions. Conclusively I am calling this car good, and the Throttle Position Sensor is the what I am calling the fix. There is a very slight, nearly imperceptible power loss at very low rpm and throttle input (almost feels like the throttle stop is too low and the butterfly is sticking, as a relatable sensation.) I know this is not the case as I have recently adjusted the throttle stop and it still checks good. 99% of drivers wouldn't even notice this, only me because I am hypervigilant to the symptoms. Will be updating the Original Post to reflect what I have found and point to the TPS. Hope this helps someone in the future.