I have a 1990 carbureted D15 that has a backfiring problem that comes and goes. I have taken it to two mechanics that have said there is nothing wrong with it. I start it up, and it runs fine then loses power randomly and backfires with a check Engine light. It usually happens @4k rpm. Some times turning the car off and turning it back on fixes this. I set it up to read the code, and it shows no code. Mechanics say the same thing. Car has no codes.

Last-night driving home it was rough and I had the problem occur again. Drove it to Honda dealership and all of a sudden the problem is gone. Here we go again. Could not get the car to run bad, so I drove it home.

Prior to this issue, a bolt broke off the distributor and the mechanic replaced. Car ran fine for 2 weeks until this issue popped up last week. Would just buy a distributor and replace but don’t want to just keep throwing money at it with out some opinions.

List of parts I have replaced
plugs
wires
O2 sensor
fuel filter

Any thoughts on what this could be, or ideas as to the next step?

All the points look clean and the rotor looks brand new. Top of the cap look like it has flow lines in it when it was made during injection molding process. May have a hair line crack on the flow lines. Had this problem on my S10 pick up. Didn’t find until I had the truck running and inspecting the distributor and shock the **** out of myself due to the current escaping the cap. Would be to coincidental this happening to me again on a different vehicle.