I have a 1987 I6 that will start and idle like a new one. However, after about 2 minutes, it will go so far out of time that idle is impossible. It backfires and then quits. (I have put a timing light on it to verify this) Let it sit for awhile to cool off.... and viola, idles like a new one again.

I have replaced the plugs, wires, cap and rotor.... even put another distributor in.... any ideas would be greatly appreciated.

 

Have you checked your coil yet.

 

nmanley80,

No, I did not check of change the coil. I put a timing light on and started the engine. I simply let it idle. At first, the timing marks lined up fine. After a few minutes, the timing marks began to seperated. Within 3 minutes the timing mark would not show up. The engine begins to miss and backfire. Eventually it will stop and not start.

Let the engine sit and cooldown. The engine starts back up like fine. I am sure that this is a temperature related problem, but I cannot figure out what to change next.

Thank you for the suggestion. I shall try it.

 

Timing changes can only occur in a few different ways. You've eliminated the distributor itself with the change so I would suggest looking for a vacuum leak. This would account for it taking a few minutes before the timing goes wackie.
Also you can try leaving the dist. bolt loose and start the truck. As it warms up try turning the dist. as it starts to backfire to see if it will clear. If it does, let it cool down and try and start it again with the dist just where you left it after the adjustment. The verify your timing marks.