This is my '89 GMC show truck with 60,000 miles on it. The truck SOMETIMES has a slight miss while cruising. The thing is SOMETIMES it misses and SOMETIMES it doesn't. Here is what I have done:

1) Changed fuel filter... No change
2) Checked plug wires after dark... Not a hint of arcs anywhere.
3) Changed coil wire... Nothing
4) Pulled every plug and all look great.
5) Tightened up every rockerarm 1/8 turn... Nothing
6) Loosened up every rockerarm 1/8 turn... Same.

I've got one idea left... the Accel coil. This wouldn't be the first Accel coil to dump on me. One in Redbird did too.

ANY OTHER IDEAS FRIENDS???

HINk

 

Get a new truck

 

Id start with...
Mixing up a salt water solution in a spray bottle and with the car urrrrrrrr truck running start spraying the mixture on the cap then follow the plug wires then hit the coil.
You will find out if you have a weak cap or wire real Quick...IT WILL START MISSING when the salt water takes the spark to ground.
....tech tip #2 for the day

"DON'T GET YOUR SELF WET WHILE DOING THIS"
YOU WILL BECOME THE GROUND

 

Almost sounds like the pickup in the dist. is going bad. Check everything else then check the pickup.

 

Sounds to me like the egr is going bad. I have seen this alot when cruising the egr kicking in and out. Feels like a miss. Take it off and clean the carbon out and replace the gasket.. If there is alot of carbon then clean the passage in the intake. Sometimes that is all it is. Just my .02

 

Hink have you checked your ignition module?

 

also consider the distributor itself, I have seen bushings with too much play(from wear) causing the pickup coil/ ignition spark to become erratic and cause lots of wierd problems

 

I had the same problem. Did what he said. Found the problem.