The car has a 1999 Corvette LS1 with a Turbo 400 and 308 gear in the rear end. It usually starts to miss for a couple seconds when I'm driving about 75 to 80 mph then catches back up. When it does this there is also a weird smell that comes and goes with the missing. Then after about 17 seconds it starts to miss again. At this speed the engine is running about 2900 RPMs. Before this started I replaced the O2 sensors, and I just replaced the plugs (but hasn't resolved it). If anyone has dealt with this or has any idea what this might be from I would really appreciate some advice.

 

try cleaning the MAF sensor with maf cleaner from auto part store ,check plug wires for burns or cracks , also check o2 wiring for faults in installation

 

Has this car been tuned?

 

Not yet I've been driving it for the past five years and haven't had any problems until now. Though I have been thinking about getting it dyno tuned.