I Have a 95 trans am auto with lt1 and has about 160.000 miles with a tune up and plugs and a few simple bolt ons. Well i had the car sitting for a couple of months and i put new fuel in it and replaced a leaking water hose on it charged the battery up. When i tried to start it it just keept trying to start buit it wouldnt. Then i kept pumping the gas and turning the key and it finally cranked up. I reved it up to keep it on and burn the old gas. Then it started to idel good and i would give it gas and then it would stumble and the rpm would drop then go up. I let it run for 20 minutes at idel then i turned it of and fired it up and it worked. I tried to fire it up 15 minutes later and the same problem happened it wouldnt crank finally it did and it mad a big backfire with black smoke and then it stumbled and when back to ideling. I need help I need to get it driving throw me suggestions. thanks

 

Is your check engine light on?? If so, get it scanned.

Could be the IAC, maybe that is hosed up.

Also, make sure your plugs/wires are not arcing and installed correctly(right firing order).

Unplug your MAF and run speed density, see if that helps.

Could be a fuel problem maybe, fuel pressure regulator??

 

i had the same problem, how i fixed it was bought a new vacuum hose that goes it the trottle body to the evap. it could be something else but its so easy to see its worth a look.