I recently put a new engine in my '65 mustang (200 ci L6 3.3L). I put new spark plugs, new plug wires, new alternator, and a new coil. New fuel filter, new air filter, new gap in the distributor, and rebuilt the transmission myself (works beautifully now, C4). The car wasn't missing before I took the car in to my shop to rebuild the tranny, and when we started it up after we had finished with it, it was missing really bad. I pulled all the plug wires, blew off the dust, made sure it was idling okay, timed it, and then I noticed that the accelerator return spring wasn't holding the throttle all the way closed. Replaced the spring with a dual-spring throttle return, and it works better, but the carburetor linkage was a bit bent, so I fixed that and now it's closed. Sorry for the long history, I want to figure this out badly! I don't know why it's missing, and any direction to move in so that I can get it to stop missing would be great. Thanks!