if you dont get it figured out and dont mind trucking it up here i can give ya a hand one day. i have timing light and about anything else here if that helps ya .... im in taylorsville ky 40071 right by the lake check and make sure all your wires are getting spark down all you need is a spare spark plug lay it on valve covers have some one crank and watch it... also wouldnt hurt to pull all your plugs and see what they look like... if they look uniform wouldnt hurt to take a quick compression test while there out.. i know you havent messed with any of this other than the intake and dist.. have to start at the beging and work your way to the problem ..

No such thing as limp mode on a TB IV. 99% of the time if the module goes bad, there is just no spark. The other 1% it just does not advance.

It could be anything in that mess of wiring. That ground wire laying on the plug wire might even be causing an arc or short. Maybe removing the dist cap caused a plug wire to crack. There are a dozen maybe's and if its not timing, then all the ignition wiring will need to be gone through.

I had a new rotor that wouldn't tighten square one time because of rust in the peg holes and a cap that wouldn't because of plastic flash.
Has anybody mentioned the ground wire yet?

Hey, could be the ground wire.

i once was working on a outside sales guy company truck he wanted a tune up truck ran decent had a hole size of a dime in the dist cap ac delco part.. i replaced it with plugs wires and new cap and rotor of some generic part supplier the new cap made the truck miss and run like crap put the old cap back on and would run fine..lol new cap didnt have any problem you could see what so ever .. just goes to show..what can happen

Did you get this running properly? If so, what turned out to be the issue?

So what ever happened here, must have figured it out by now.