So my 94 Z has an interesting missfire. In the morning I will start off in first gear and after 1500 RPMs the car feels like it is missfiring on at least two cylinders, but when I shift into third it goes away. It wont come back for a couple days, but now, it has a slight "chug", for lack of a better word, at any RPM, any gear, any load. I have no idea whats going on. It has new wires, plugs, and cap and rotor.

 

Did this problem start right after you changed all the stuff or after some time?

 

After a while. I don't know what's happening.

 

I figured out the problem. For some reason my #1 spark plug had backed its way out of the head and became loose. I tightened it up and the problem was fixed.