i have a 91 z28 that wont rev pass 4000rpm. i had my trans checked out and was good. any advise would help.

be a little more specific. Does it feel like the power just took a dive off the deep end? Or does the engine more or less hit a brick wall so to speak? Your description is a bit vague and could be anything from valve float to a clogged cat to poor fuel delivery (clogged filter, dying pump, etc). My guess is it is along the lines of the later 2.

*edit* Welcome to TGO

car stays at 4000rpm "doesnt matter what gear it is in" unless i ease off the gas so that it can change gears and once it reaches 4000 again it stays there and wont rev any higher. new 255 fuel pump, headers, cat, exhaust, ported heads and intake. was reading articles in hotrod mag and came up to two articles that mentioned valve float. when car was reving right it would rev to 6000 before releasing gear.

So its not like it just loses pwoer after 4k, its more like a rev limiter at 4k? Does it make any odd noises (short of not shifting)? If you let it sit there at 4k, does it EVER shift? Only few things i can think of at the moment are a misadjusted, loose, etc, TV cable or a governer issue. What happens if you manually select gears?

Valve float wont prevent an engine from revving. It just loses power.

no odd noises, but when engin is cold it runs fine but as soon it warms up it starts acting up. the trans shifts fine when driving normal. but i like to drive hard and when i floor it thats when the problem starts. i tought that the trans wont shift until it hits a certain rpm at WOT and thats why it wont **** since it cant rev pass 4000