I'm the original owner of the car, this problem started on Tuesday morning on my way to work, and I haven't been able to find the problem, so a little help would be appreciated.

2001 Type-R
Wiseco ~12:1
Stock Cams
290cc/min injectors(‘97+ Prelude)
HyTech Header & Exhaust with Cat
Hondata S300
J&S Safeguard
vtec is set to 3750

Problem:
Idles fine
Free Reving is slow to respond
Acceleration is really slow in the lower RPM ranges, as it passes through 2500-3500rpm you have some stuttering, when you go over the vtec switch point it gets slightly better, over ~4500 rpm is still slow acceleration, but the car doesn’t stutter.
Cruising at low throttle %, when you have a low load on the engine, slow rev, no stuttering. When you increase the load, the stuttering/bucking is apparent. When you go past ~4500 rpm you have no stuttering/bucking, cruises fine.

Things that we’ve already tried that haven’t changed anything:

Rotor/Distributor Cap
Plugs
Swapped the Distributor with a known good distributor
Reinstalled OEM 240cc/min injectors
changed vtec switch to 3000 rpm

Things to try tonight:
“fresh” Hondata B18C5 program
OEM Ecu reinstallation

 

Have you checked your TPS sensor?

 

I looked at the throttle % via Hondata, and also looked at the TPS logs, they looked good. I'll review them again when I return home to see if I might have missed something.

 

Try disabling closed loop and retest. It sounds like an O2 feedback problem (either faulty O2 sensor or wiring).

 

X2 tps sensor. Test you voltages with a multimeter.

 

tested plug wires? checked cam alignment?
fuel pump gave me some stutter when it was on the way out.
dorman tps ftw, f u blox! 8(

 

Update - problem still here, items that I've since tried:

TPS readings - fine, across the entire sweep of it's movement from 0% throttle to 100% thottle, viewed while at a standstill, then datalogged a 5 minute drive via Hondata, both show good numbers.

O2 sensor - went from Closed Loop to Open loop, slightly better idle, but no change in driveability...even after resetting the ECU short/long term fuel trim.

Hondata Program - used their '01 itr program, no change.

ECU - swapped in the OEM ECU, slightly better drive ability(tells me that I need to redo my tune), still have the stutter. Codes 65(no secondary O2 sensor equipped), Code 1(primary O2 sensor must be bad, but I can turn it off in Hondata for now)

J&S Safeguard - removed when swapping to the OEM ECU, as it's connected to the OBD2b-->OBDI harness adapter.

 

I would still check your TPS sensor with a multimeter for proper voltage, another thing to check is your MAP sensor

 

MAp sensor failure.