I have a 1990 RS Camaro original 305 throttle body. I bought a 93 350 Caprice motor and put a early LT1 cam in. We pulled the old motor and put in a the new motor. When we had apart the distributor apart, the eight point magnetic plate on the shaft fell off. Trying to save money we piened the shaft and got the plate to stay on. We finished dropping in the new engine and started it. We advanced the timing between 4 to 6 degrees for the best idle. I drove it for about a day and a half and it started to run terrible. We then discovered that the plate was spinning on the shaft. We replaced the whole distributor and it still runs terrible. Since it is computer controlled and has a bypass wire for the timing, it must be unplugged to time the car. With the bypass uplugged it runs but with it plugged in it will not run. We have discoverd that when we icrease the rpms, instead of advancing the timing it retards the timing up to ten degrees at high rpms. We have replaced the pick up coil, the ignition module, the knock sensor the chip, the ecm, plugs wire, plugs, cap, rotor (basically anyting related to the ignition system) and the problem still exists. I am lost and the dealer here cannot even figure out what the problem is. If anyone can help I would appreciate it.