2000 Pontiac Firebird engine problems

[Unregistered]

My boyfriend has a Pontiac Firebird and it has been missing a little every once in a while when he is driving it. It would miss when stopped at a red light or going on the interstate. Yesterday the car was missing pretty badly and had a loud sound coming from under the hood. He last year changed the coils and also last year changed the spark plugs. Do you have any ideas what it might be?

 

[Tresker]

Check a spark plug and see if its fouled.

Is the service engine light on?

Make sure the plug wires are on good. Maybe they need to be replaced.

 

[TropicDave]

Also try some injector cleaner, he could have fouled fuel injectors. Check the filters as well. Should be in either the fuel or primary electrical systems.