'00 LX manual. bone stock other than a trashy eBay header.

in stop-and-go traffic i get an intermittent high idle (1800-2500rpm) in neutral. also, when cold (first start in the mornings) or after making a stop and restarting (going to a store, sitting in the parking lot cooling) within the first 30sec or so of driving the engine cuts out momentarily like hitting red line fuel cut. It may be fuel cut or ignition cut, not sure. otherwise car runs great.

idle speed and ignition timing are in spec and set according the the FSM, new spark plugs installed, TPS output is normal at closed position (didn't check WOT yet), coolant is full, temp is steady 195 according to my scan tool, IACV passed functional checks (idle drops when disconnected, strong pull from TB port. fuel filter has been replaced in the past year, MPG are normal, power seems normal. no other symptoms, no CEL.

any wild guesses or other things worth checking?

 

I had a similar issue after re-installing my d series. It ended up being a multitude of things, such as the TPS being out of calibration (I saw you checked yours) but the other being the IAT sensor harness being swapped with the purge solenoid device. Ended up frying my IAT which caused the idle to be much higher than normal. Check to make sure that your throttle body is clean, as well as your throttle cable isn't sticking. Those are the first things that come to mind.

 

Check for vacuum leaks as well.

 

Did you clean the IACV? Test the IAT and ECT sensors with an ohmmeter see if the resistance matches the expected value for the temperature using the chart in the FSM.

Also the throttle cable could be sticking. When it idles high, pull over and open the hood and push on the throttle linkage to see if it is stuck partway open.

 

thanks for the brainstorming jump-start everyone. i'll get at it this weekend and see what i can find.

 

this was it.

watching live data from my scan tool i could see that the throttle was staying open (2-3%) when my foot was off and the engine speed was above idle. new cable installed, all is back to normal.