I Have A Serious Problem With My 95 Z28 When You Start It In The Morning It Runs Great But After It Is Warm And You Shut It Off And Then Restart It 20 Minutes Or So Later It It Acts Like It Is Starving For Gas You Can Push The Gas Pedal And It Will Slowly Rev Up But It Pops And Acts Like It Has No Timing It Will Not Make Enough Power To Move. It Will Do This For About 3 To 5 Minutes And Then The Pedal Will Start To Get Responsive Again And It Will Rev To About 3000 Or 4000 And Then Slowly Regains All Power The Only Thing It Does All The Time Is It Does Not Want To Rev Past 4800 Without Feeling Like It Is Stumbling. I Have Replaced The Opti,plugs,wires,fuel Filter,air Filter And Checked For Vac Leaks I Can Fix Most Anything But This Has Got Me Confused Any Help Would Be Great!!!

 

Mine did a similar thing.
Turned out the plugs were so fouled that getting good spark was a problem
I replaced the plugs, plug wires and O2's and it has been good ever since.

Any codes?
How many miles?

 

It sounds to me like after your vehicle exits closed loop (where the ecu runs the engine off preset "ideal" sensor perameters), your engine struggles. This can easily be attributed to a number of things, however some are more likely than others. I would start with the sensors (specifically the oxygen sensor(s) working through to your crank position sensor (if its a 95-97). If you still have EGR, your cat or EGR solonoid could be clogged. It could also be pulling timing because of knock or false knock (which could be anything from a bad exhaust rattle to excessive engine noise). This, however is less likely because the ecu can effectively pull UP TO 22 degrees of timing and the symptoms in which you have described are far more extreme than 22 degrees. You could have dirty or clogged fuel injectors or low fuel pressure. (Check for proper operation of fuel pump). It could also be incorrectly gapped plugs.

I hope this information helps.

Charlie

 

I Will Try The O2 Sensors The Car Has 160000 Miles On It And I Bought It From A School Teacher That Drove It 120 Mile Round Trip Everyday To School It Is A 6 Speed And We Had It To The Track Last Fall Went 14.60 At 97 Mph So The Car Is Still Strong