So I picked up a 1994 Discovery as an accessory donor for my 96. I dont really have the place for a parts vehicle and because this thing is in such great shape, I would prefer to sell it. The service records on this thing for the past 5 years is over 7k!

Very few leaks, great body with hardly any rust, good interior, CDL works great, new PS system and lines, new brakes with master cylinder and rebuild brake booster, New Diehard battery, New Heads 30k miles ago, etc, etc, etc.

The problems:
Backfires but there is not CEL. the idle is "OK" (fluctuates between 750-900), and when you run the RPM up to 1500 it will "pop" with a backfire from both the intake and through the exhaust. Also when you begin to drive it over 5 mph it backfires heavily.

I have seared and swapped out fuel pumps as another post seamed to have similar symptoms but it did not resolve the issue.

Possibley timing?
I do not own anything to test it but I could run down and pick something up. I fear a worn cam, but wouldn't that at least through some code? If it were bad plugs or wires, would that not also through a code with how bad it is?

My dilemma is Im going to be selling it and I don't really feel like throwing a bunch of money at it. If anyone has any ideas on diagnosing these early trucks I would be greatly appreciated!