here is the problem, when i give my car more than 1/2 throttle, i get a stumble and noise that sounds like what i think is an exhaust leak, however there is no hint of an exhaust leak if i don't give it more than about 1/3rd throttle or at an idle. is this how an exhaust leak would normally act? or could it be something bigger, like a failing Optispark or collapsed lifter? i ruled these 2 out at first becuase of the amount of noise it makes. anyone have any suggestions?

 

possibly a burnt wire. Check to see if all the spark plug wires are on the plugs all the way. I was having a similiar problem and found that one wasnt on all the way....fixed the problem.