Why does car idle rough and surges when stopped?

DAN423

MEMBER
1996 CHEVROLET CORSICA

My car will idle good at first then it starts to be irratic. When I drive and come to a stop it surges forward. I've replaced one coil, the TPS, checked all vaccum lines for leaks. Still runs the same. The coil did help solve the problem and ive checked the other coils they seem ok. Any ideas at this point would be greatful. Thanks

6 Replies

HMAC300

MECHANIC
48,601 POSTS

Try cleaning throttleplate and iac valve hole with choke cleaner and see if that helps. Clean throttle plate on both sides.

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Monday, June 4th, 2012 AT 4:31 PM

DAN423

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4 POSTS

I just did that today

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Monday, June 4th, 2012 AT 4:35 PM

HMAC300

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Ok then scan for codes and check fuel pressure. Then check for vacuum leaks. Make sure the throttle plate is clean on both sides though with no residue and wipe around inside of where plate touches. Also you can't have any holes between the throttle plate an dmaf sensor.

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Monday, June 4th, 2012 AT 4:47 PM

DAN423

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The check engine light is not on will there still be a code to retrive? The only light that is on is engine coolant but that has always been on since I bought the car

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Monday, June 4th, 2012 AT 4:51 PM

HMAC300

MECHANIC
48,601 POSTS

It cold be an idle air control valve then if you have done everything i've suggested. You should fix the engine coolant light as that could give aproblem as well. But recheck for codes, most auto parts stores do it for free.