I just bought this car my second Z the engine is a lt1 and we are having problems. There a major miss in the engine at times you get to a traffic light and it feels like it's going to die out , run very rought and sputters.
Almost feels like it's to rich in fuel, it put in a new gas pump new Egr , new plugs.. what else might cause this? thanks

 

plug wires, knock sensor/ks wires could be bad, 02 sensor/s or sensor wires could be bad.

 

Could also be the optispark distributor. When mine went bad, the engine would chug and the car would shake back and forth when idling. It would sputter when driving, and be almost ok at higher rpm's. It's common for the opti to crap out on these engines. And, because of how it works, age can have as much to do with it as well as how many miles it has on it. But...I would change the plugs and wires first, it's a little easier to do.

 

low end sputter or miss??

Go with the ZERO cost visuals first


is there any oil or coolant drips coming from a front seal of the water pump?

If you have stock exhaust manifolds, I'm sorry to say this but go back, make sure you did not crack any of the insulators and be sure the wire boot goes "click" when you seat them. Also, why didn't you replace the wires (less than $40). Again, with stock exhaust it's a PITA


next, check for any vacuum leaks

that's the low cost stuff


one more question, if you disconnect the battery for 10 minutes, then when the engine is COLD, does it still "miss" while it's in open loop or does the missing occur when the engine warms and it enters "closed loop"?