1994 Z28 convertible, 149K miles. Bought this car about 3 months ago. Previous owner said it sat a lot over the last couple years, so there was some TLC necessary. So far I have had to replace the following: fuel filter, thermostat, valve cover gaskets, flush heater core, and the entire A/C system. Everything I have done has (more or less) solved the issues I was trying to fix. What I'm faced with now is that when accelerating off the line or trying to hit "passing gear" (automatic transmission) the car bogs down, feels sluggish, and sometimes bucks a little. This is NOT noticeable when the engine is cold; only really happens after prolonged driving (30min +). I'm not flooring the car either; really only 1/2 to 3/4 accelerator pressure. My buddy is a former mechanic and has given me his thoughts, but doesn't want to just "throw parts at it" in hopes something works. Any ideas?? Optispark? Fuel pump? ??? Thanks for your insight.

 

first check your fuel filter. it may be that stuff in the tank has made its way to it. take it out and dump the contents in a clear container. dump it out from the tank side. if clear then time to check the fuel pressure.

 

look at 5 and 33 here 4th Gen LT1 F-Body Tech Aids

 

may need a trany flush filter cleaning or replacement ,over drive is for like 60 or more higjhway driving