Yes!! You are vindicated...lolSo, it might actually be an amp amp draw?
I am vindicated!
But seriously, why would several radios do the same thing plugged in if the problem is not there unplugged? Are the harness and individual connectors ok? Has the wiring been messed with?
Well, as far as the question goes, the first radio I tried aside from the OEM stereo, while having the same plug ins, it is not a Fox Stereo, which I realized after looking at it again. The second stereo, which is an aftermarket Sony, came out of my '92, but if memory serves me correct, you have to bypass the factory amp to use it.
Mustang5L5 (Mike, I believe), thank you for that information. I did not know that the factory stereo would work without the amp, so that will make it easier to narrow down. I know I have another OEM Fox Body stereo floating around here somewhere. I will update once I can verify.