Re: 93 T-Bird ramps to 3500 rpm ?
My 85 bird did this for a while and it turned out to be a carb issue.
The throttle linkage was bent, and when I hit the gas it stuck open. You may also want to check the throttle position sensor.
A friend of mine had an issue similar to this and his has something to do with the cub idle sensor?? His just idled to fast, not sure what he did, the older (80's) birds had what was called a curb idle sensor, it was used to control the throttle position when the AC kicked on, not sure if your 93 has the same set up, doubt it, but it something to look into.
Hope this helps.