my car has been surging since i could remember. when i first got the car it ran like a champ. then i got ebl car ran even better then swapped to l98 had a surging problem in cold starts and would surge in stop and go traffic. then my tranny crapped out so i swapped a t56 and unless i gas it a little the car will die on me on cold starts and will sometimes die coming to a stop. i replaced thermostat to a 180, 200-185 fan switch. it has shorty headers and full exhaust. i replaced the iac, the tps, and the ignition module, changed to a 190l pump. i brought it to a mechanic to see if he could find something i couldn't he changed the gaskets and it ran better for a week. i replaced the vacuum hose that goes to the canister cause it was bad. what else havent i checked? it idles low and dies and sometimes idle high on start up and stays at a high idle unless i press the gas pedal.

 

First thing to do is to adjust the idle stop screw to get an IAC counts of between 5 & 10 steps. This is on a warmed up engine with no other loads. Can use the WUD to see the steps.

Likely need to open the blades some to get the IAC steps down. In this case as the screw is turned in the ECM will drop out of idle mode. The WUD will also show that. IN this case it is best to crank open the screw say two turns, then start the engine and adjust from there.

RBob.