i've just got the new bottom end in and the car (98 wrx by the way) cuts out some (most) times when i come to a stop or turn a full lock etc, it ideled at 600ish before, i turned this up after a day of driving as i gave up on the ecu self learning,to about 1000revs but it still cuts out some times and the stepper moter is very slow to react,when i stop some times the idle is so low the rev counter dose not reg, and when restarted it revs very high for a bit till it settles, do these ever need cleaned? if so how if not then whats up?

 

do you have a aftermarket ecu ....... it might be the mapping it you have one

 

no its comp standered with an exaust

 

I think you will find the standard ECU did not come with an exhasut!