pretty sure i have computer/wiring probs. HELP!

Well, I'll try and help you out as much as I can. first, I have NEVER heard of anything so weird happening. Damn thing sounds like something out of a sci-fi book. Ok, I'll cut the jokes.. but seriously, it sounds to me like a very loose main harness to the PCM (computer) . But what I don't get is the radio problems. Or the brake pedal causing the Tach to go to zero and making the radio emit odd noises. This isn't normal man. The radio isn't even wired in any way to any of those components nor is it wired to the computer. Not like on the much newer Mustangs. Do you have any sort of alarm installed? Factory alarm even? ANtitheft system. Check the interior fuse panel wiring and make sure nothing has started to come loose. Also check the wiring to the Distribution Box under the hood, behind the battery.

Have you noticed anything else? lights coming on? other strange behavior or noises? Has anything ever acted up before ? I need to know anything else you may gave experienced. This is not normal 99 Mustang behavior.

There is a ground (G204) located behind the center console. This is a very important ground that is shared by a number of devices including the cluster, radio, and GEM. G204 is frequently messed up during a radio install.

IMO, likely the slow re-start was due to anti-theft (PATS). Where does PATS get it's power? If you said the cluster, give yourself a gold star.

The one thing all of your problems have in common is ground G204. If this were my car, I would start there.

wmburns...good catch, but that still doesn't explain the brake pedal to radio making noises. I've done lots of work to these cars, and never have I run into something like that. Something is feeding audible noises into the radio for some reason. That's just weird.