I recently purchased an 86 Ramcharger Royal SE and Im having hell with this truck.
It fouls plugs because its running rich i suppose. I have had Gary Briar( A knowledgable carb ad dist guy) Rebuild my card. I put a new fuel pump and filter along with a HEI Distributor tpo discontinue the SCC System. Still using the factory Coil but having problems stalling. I have a new ballast resistor but cant locate one on my truck. I have put on a new fuel tank. Removed the faulty charcoal canister and have never had the smog pump hooked up??

 

Here's a couple thoughts to keep in mind..

1. Fowling of plugs because of running rich is unusual. Do you see a lot of unburned fuel in the form of black smoke from the exhaust? How many miles on this vehicle?

2. If the plugs look black and sooty to the point of fowling, then I suspect the fowling is coming from unburnt oil not fuel. Given the age of the truck, valve guide seals may be a culprit. The worst case scenario would be one or more of the piston oil rings are worn out. One easy way to spot this is to have someone follow you as you go down hill. Once up to a good speed, take your foot off the gas and downshift at least one gear to cause the engine to increase RPMs while slowing the truck. If the person following you sees blue smoke out of the exhaust, then one or more of your valve guide seals are shot. Time for new guides and seals. May as well have the valves and seats ground while you have the heads off.

If while the same person is following you going up hill, stomp the gas while in a lower gear and high RPM. If blue smoke comes out of the exhaust, then chances are your piston oil rings are shot. Time for an engine rebuild.

One last question: Do you typically only foul certain plugs? Or does this happen pretty uniformly to all?

Good luck!