Strong gas odor

I have a 95 olds cutlass supreme 3.1, that was on jack stand (front) for about 2 months when i did remove the stand and drove it, it started to feel real "heavy" and I get a real strong gas odor from exhaust? I cant figure out what it could be....HELP

1) Is this car running on all cylinders?
2) Is there a Check Engine Light (CEL) on?

Just a check make sure a rodent didn't build a nest in the air intake duct. This would result in poor air flow at higher rpms. This would show up as a CEL. I would think that the PCM would reduce the fuel injectors to eliminate as much as possible the amount of fuel into the engine to match the air.