So I have a 95 z28 and it will run fine for a while then sputters and occasionally backfires. After that it will run fine, but may sputter again. I think it's the opti since I've seen this before with this car (twice). Fixed the water pump so it wouldn't leak down onto the opti last time. Also no vacuum leaks. New TPS, starter, and new gaskets and seals because I had to fix an oil leak. If anyone can help let me know.
Thanks

 

Have you scanned if for codes? Have you checked the fuel pressure?

Under what condition does is "sputter" ( = misfire ?? ) - idle, part throttle, WOT, all of the above?

Trans type?

Any major mods?

 

I was thinking the fuel pump too. Any easy thing to check with the right tools. You would need to tape one to the windshield to be able to see if the pressure drops at higher rpm's.

 

Fuel pump fine and filter fine. It sputters during acceleration sometimes. Most of the time it's when you're cruising at a constant speed, and then out of nowhere it sputters then keeps going. Have to take it to dealership to get codes read because someone put an OBD2 connector on an OBD1 system. Also the car is all stock.