alright this is long. i got car back from shop who replaced clutch. clutch was messed up from pulling out of shop with speedometer also broke. thats a different issue. after about 2 - 3 weeks of driving not even boosting because car was running lean and turbo not spooling up till 5000rpms for some reason but car was drivable. last week i was parked and the revs dropped and car almost stalled at a red light 2 times. drove home parked it and the next day same thing it would surge and rpms drop with car almopst stalling and sorta breaking up or bogging while driving and it sounded like fuel pump was cutting in and out. i replaced fuel pump and fuel filter car still continued dropping revs. i found a vaccum hose unhooked going to intake manifold. hooked that up. they say it seems like a vaccum line is unhooked or bad but i went over all lines. i replaced my 415cc injectors with my stockers and cleared my service engine light so i can pass inspection because i was only throwing a rich code. i figured maybe my injectors were bad. well its still idleing funny and dropping rpms at idle.im not throwing any codes and replced my plugs and wires and thermostat because after putting my stocker injectors back in i drove 10 mins and car over heated. i have no idea what to do or who to turn to for help. what could it possibly be causeing my car to surge like that. im not sure if its over heating anymopre since i changed thermostast. maybe a map sensor going bad??? please any suggestions would help

Crank or cam position sensors. I'd say more likely cam. I'd inspect the magnet on the end of the cam where the sensor is, then replace the sensor if necessary. I had a similar problem with my crank sensor.

update. i replaced most vaccum lines and the sugreing stopped. the only thing is i hav to lean the stock injectors out to -10 at 1000rpms for the car to idle or run right i do not know why i should have to lean stockers out for one? 2. the car overheated again after replaceing the vaccum hoses. why could it be over heating like that. under boost it falls flat on its face and goes lean at 5000rpms. im not really worried abotu the boost problem now but i need to findn out whats going on with the overheating problem. i thought it might be to lean while leaning the afc out for stockers but its only -10 at 1000rpms and it shouldnt be lean like that. please someone help i need to get this thing runnning so i can get to work i dont know what else to do unless maybe the water pumps going bad but before the sputtering and surging problem it wasnt overheating so i dont think the water pump could just go bad like that. any suggestions please.

Originally posted by sike
Crank or cam position sensors. I'd say more likely cam. I'd inspect the magnet on the end of the cam where the sensor is, then replace the sensor if necessary. I had a similar problem with my crank sensor.

would the sensor make the car surge and overheat? could my map sensor be bad? im still throwing no codes.

i had a bad radiator causing my over heating problem, it wasn't leaking but the fins were falling apart. just something to look into.

Your motor's rpm surging and dropping are opposites. If your just saying that your rpm is dropping, and your fuel and ignition checks out I would check what temps your IAT sensor is seeing. My car was doing the same thing, no codes, and I saw that my IAT was reading the manifold air temp. as 60* when it was 90* outside, which should make my intake temp around 115-125*. My car would bog down trying to boost, and die at traffic lights.

so what should i replace the iat sensor. i fixed the surging problem when i replaced all the vaccum lines but its still over heating. rpms just just a little bit not much at all and barley ever but its still over heating. someone said it might be my fans arent coming on or my collant temp sensor. any other suggestions?

If you have a scan tool or pocketlogger you can see the temp your ECU *sees* and compare that to your gauge, as the motor uses a seperate sensor for the two. Your fan should kick on when the motor is warmed up (206*) sitting their at an idle, if it doesn't then this is your problem.