This is a 1995 z28, built 383 with about 20,000 miles on it. At idle the rpms will bounce from 1000 to 1500 sometimes it gets lower and the motor just dies out. When it does this it'll take a while of cranking over until it fires up again and then throttle response sucks, i'll punch the gas and it'll stumble as it rises in rpm. While driving it'll stumble like this and looses power horribly. The car sat for maybe 3.5 months, could the gas have gone bad within that time and done damage to the fuel system? I also noticed a funny rotten egg smell and its not an exhaust without cats like smell, it's slightly different. Anybody have any thoughts on this? Thanks.

 

Gas shouldn't go bad in 3.5 months. I'd drain the tank anyway and put in some fresh gas to rule it out as a cause.

 

Just noticed that if I unplug the MAF sensor, it does not stumble nearly as bad as it was with it pluged in.

 

A couple of things come to mind from the problems you seem to be having,

1. Optispark
2. Fuel Injectors could be dirty/going bad
3. Fuel Pump going bad.
4. Check your fuel pressure, make sure it's around 43.5psi I believe
5. Check all plugs/wires to make sure they aren't fouled.

PS. Gas shouldn't go bad in 3 months, especially if it is 93+Octane Gas

-Dax

 

Does it sound like it is misfiring at all or just surging idle? Did the car sit in the open outside?

 

Sounds like the problems I'm having with mine