Ok guys, so i have a 94 z28 and it just doesn't wanna go. When i first got the car it had the wrong plugs in it and it would miss and studder whenever you were under 1500 rpms. I put the E3 plugs in it and it doesnt ever miss anymore but when you give it gas it just doesnt get up and go like it did at one point. It had lost the power before i changed the plugs so that isnt it. The thing is, it runs great every now and then. Last week i lit up the tires in third and the day after that it was so sluggish i didnt want to drive it. It has NO power under 2000 rpm's and after that it just isnt like it should be. Any ideas?

 

Check engine light on?

 

I know you said the plugs aren't your problem, but for the record, E3 plugs suck!
Have you ever changed your fuel filter, or air filter?
And since it gets beaten like a dead horse around here, I'm not even gonna mention the possibility of a restricted cat converter...maybe someone else will.

 

ditto camaro69, those e3 plugs are garbage. me personally i like using AC Delco platinum plugs...are about $6.50 per plug. like camaro69 said check your filters. hopefully this isnt a sign of your opti starting to go

 

The fuel filter is brand new, there is no cat, and the air filter is a new K/N. As for the check engine light, it usually stays off. It pops on maybe like once a week. I've been trying to find out what the knock sensor should read on a good running motor. I hooked it up to one of the nice diagnostic machines and it read like an 80 something on the knock....i was thinking it might be killing my timing. Thanks for the input guys, keep it comin!