Random misfire when hot

I have a 91 2.6l that came out of a rwd, and I recently put it in my 90 4x4 b26. It been about a month and everything has been working fine. Today I was driving it home when it got a little overheated, just under 3/4 on the temp gauge and it started missing here and there. It wasn't bad like a full miss but it was every other piston cycle. When the engine cooled down it stopped and ran fine.

The engine has 74k miles with new spark plugs, spark plug wires. The truck has almost 400k but the prev owner replaced the ecu. The clutch fan is going bad and that's why it overheated but I have a new one on the way.

so my q is what could cause the misfire?

Another thing is when the I turn the lights on, dash light flicker for a couple sec or don't come on at all and then work for the remainder of the time. what could cause that?

Also the windshield washer wont work anymore. It used to but there is no power going to the motor anymore. The motor still works because I tested it.

Have you changed the distributor cap lately? The seals around the input shaft will wear and oil/or fumes will find their way into the distributor, coating the interior of the cap, causing misfires.

Checked the fuse for the wipers?
Check voltage in the wiper plug with the wiper switch turned on. If fuse is good, and no power at the wiper, check for power to and coming out of the wiper control on the steering column.

Dash lights, a gremlin?

Or might be a lose connection somewhere, at the light switch, the dash light dimmer, or the plugin for the instrument cluster, even bad light switch possible.

"Don't sweat the small stuff."

When you get it hot, you're going to get pre-ignition and/or detonation - evidenced by knocking and pinging. Keep it cool and you won't have that problem unless you have some other issues.

The thread title says "random misfire" but you describe it as "every other cylinder cycle."


Congratulations on 400K miles on the truck. With that many miles, your lighting and washer pump issues are most likely caused by a dirty and possibly worn out combination switch - the housing on the column that holds all of the other switches (parking light, head light, turn signal, hazard, wiper, & washer pump.)

They are usually just dirty and can be cleaned up. ABE has great thread on taking it apart and cleaning the individual switches here:

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On the wiper side of the switch, I detailed the wiper/pump switch starting on post #15 of this thread:

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If your wiper fuse is good (or the wipers work), then I would pull the combo switch and give the individual switches a good cleaning. This is a very common problem - although usually more common on the light switches than the wipers.

Thanks for replying. I took the distributor cap off and the rotor was rusted and the points were worn down. The engine that I took out of it that was blown had a new cap and rotor so I switched them. The engine had been sitting for 10 years so it needed some help. I put some Lucas injector cleaner so now it runs smoother and quieter.

Also I failed to specify that the windshield wipers work, it's the washer fluid that doesn't. Like I said the motor on the little bottle works, it's just when I pull back on the wiper lever, the wipers come on, but the washer fluid pump does not turn on.

The wiper fuse is good but I can't find one for the washer fluid. The housing is pretty dirty so I will try that and post what happens.

As for the flickering lights, It was the dimmer because every time I moved it a tiny bit, the lights would either flicker, turn off/on. I replaced it and it works fine.

There is a good post here on removing, disassembling, cleaning and reassemble for the wiper control, search it, maybe?
Keep on truckin.