My 94 z28 all of a sudden started running rough yesterday, I didn't think too much of it, thinking maybe it's my imagination. Well today, on my way home for break from work, I noticed it was running rough. I wasn't imagining it this time, but wasn't really that bad. Well I got home, did my stuff, then went back out to start up the Camaro and first thing I noticed was the rough running again, then I look outside and there's a ton of smoke coming from the tail pipe like I put seafoam in it or something. I go to smell it and it has a gas like smell. I immediately turned it off, called in work, and posted here. The motor only has 80k on it, and has been maintained well. I checked the oil and coolant, they look fine and not mixed at all (to suggest a blown head gasket). Any ideas?

Also, I have an extremely loose belt (alternator belt) could that have anything to do with this?

 

Theres a lot of things it could be, any check engine codes or anything?

After a little searching it looks like you may have a bad Opti-spark unit. Expensive and a bitch to change...

 

Could likely be something like a MAF sensor failure too.

 

Wow. Lot's of possible problems. Looking at ls1lt1.com / Yahoo Answers / friends, I got a total of 8 possibilities.

Headgasket (although the oil and coolant don't seem to be mixed)
Exhaust manifold gasket
MAF sensor (thanks Fabrik8)
Opti-Spark (thanks Abysalone)
Injector stuck open or leaking very badly
Bad Piston Ring
Cracked block
water pump

Someone also said checking the oil and Coolant is a basic test, if it is a cylinder you would not see it mixed.

I think best solution at this point is take it to have it diagnosed at a mechanic. Compression check should narrow it down to a few of those. Also going to try and put a white t-shirt for the exhaust fumes and see what color I get. Other suggestions?