Just bought a 94 Z28 but am having problems with it. It runs perfect for a while but after about 20 to 30 minutes it starts acting up. When i am at a stop light it will try to take off with my foot on the brake. Then once i start to give it gas it bogs down real bad. Ive replaced the idle air control motor and the throttle position sensor and the MAP sensor. What else could it be? It's not showing any codes but i scanned it anyway and nothing came up. Also had vacuume leaks fixed.

 

I'm running into similar problems with my daughters '94 Formula. I have replaced the O2 sensors, sparkplugs, coil, and gutted the cat ( in case it was clogging up ). These things only cleared the symptoms up a little. I'll be following this post with hopes we both solve our problems. But I'm afraid our Optis are on the way out.

 

How are your plug and coil wires? Are they in a wire loom away from exhaust? Check your fuel pressure too. >Jake.