wierd acceleration behaviour
 

Just have a few problems with a car I just got for xmas,
its a 94 z28 w/190,000ks on it

the car is hesitating very badly, when I hit down on the gas at a light I dont even burn rubber , an alero (v6 crap box) was able to leave me in the dust ata light lol, the RPM goes to 2000 right away and then slowly increases after that almost like its a v6 or even worse..a 4 banger lol, no engine lights have come on, one thing really wierd I noticed, after I turn the car off and let it sit, I can turn it back on and it will leave a patch of rubber on the road first time i hammer down on the gas, but...second time I go to do it, it hesitates once again,
also
when driving fast on the highway I can notice a crappy smell coming from the vents, smells almost like propane kind of, and in the engine compartment it smells like exhaust too,
today I tried to find the air filter, couldn't find one.....someone that had it before me might have taken it out, would that be causing this hesitation problem...or is it the dreaded optisparK? Its really hard to tell if its misfiring or not , Im not sure whether to replace the plugs first or what? any help would be appreciated:)
Mike

RE: wierd acceleration behaviour
 

Sounds to me like a clogged cat. The back pressure prevents the engine from revving up. Try unbolting the cat from the Y pipe & see how it runs with open exhaust.

RE: wierd acceleration behaviour
 

cat as in the cat converter? a new one was just put on so the car would pass emissions in my area so thats probably not it, when the car is in park I can rev it up to 5000rpm or more too, I noticed a hissing noise today when I took it for a drive too, its really hard to hear it, its near the passanger front seat but I will check the cat again, the car had a bad cat on it before and still performed badly:(

RE: wierd acceleration behaviour
 

There is a possibility that the old cat insides got blown into the muffler, and clogging the muffler. If the hissing is coming out of the exhaust, especially right after you turned off the engine, something is blocking the exhaust.