Stumped ..idle problem could really use some ideas

I have a 91 with a 5.7, just the past couple of weeks it has started idling really low, cold startup is normal but once it gets to normal operating temp it acts like its thinking about dieing 'though it never does' when i stop at a red light it will idle fine for a few seconds then drop to a low idle irratic lope.
cap, rotor, wires, plugs, air filter, all fresh. egr checked and good. checked for vacume leaks, none. ran injector cleaner several times when i first noticed the problem, no change. i installed a mild cam and double roller chain 8 mos ago but dont think thats the problem since in every other way the truck runs great, no millage loss, no stumbles, missing, or flat spots through the power curve,
at 170.000 it burns about 1/2 a quart through the guides/seals between oil changes but thats expected.
now as i bang my head against the hood i keep wondering what in the he// have i missed.
one other thing for the tech's out there, i thought the problem might be the coil arcing against the bottom of my air cleaner since the connectors on top of the coil rub the bottom of the housing slightly so i mounted my stock coil horizontaly on the firewall above and slightly to the side of the distributer, now i have a humming noise coming into the cab from behind the dash in the area i mounted the coil, the hardware through the firewall is free and clear of anything behind the dash,
i have remote mounted a few of my coils in the past, though never this style, do i need to isolate it with rubber mounts, and if so do i need to run a ground? i mounted it solid thinking it might draw ground from its mount.
any information,thoughts, ideas, proceedures, insults, would be greatly appreciated, im completely at a loss at this point.

The list for this is possibly endless does the check engine light come on when it goes way down? temp sensor-- IAC--TPS-- computer--(etc-etc)

Thanks bawana, a couple of those i did not check, but temp sensor is fresh, replaced when i installed the cam, the tps i have not run a check on yet the iac was my next item to go after as soon as i can find the procedure in my book,. no though no engine light, that would make things just a little too easy for me. no other symptoms at all other than what i listed. thanks for your input

if you mean "lope" like it goes low, revs, then goes low etc... then try the tps, lots of times thats the cause

Check your distributor for wobble. I had 195K miles on my engine when I learned a bad distributor (worn out bushings) was the cause of my problems.

Fuzzy, I dont know what you have for fuel delivery, but if you have installed what is called a IAC, which is idle air control, you can check that maybe and see if it all clear with no obstructions such as varnishing and deposits. Just a thought.
Joe