Erratic Idle, and Overheating!

Alright, I changed the thermostat in my car, quite recently. For some unknown reason, the car will jump up to 2000+ RPMS, and then slowly level itself to 1000. This actually started happening right after we attempted to gut my cat.
While we tried to gut all of it out some of it seems to have stayed behind..
Also, usually this never happens when the car is cold. It only happens after I've been driving for a little while.. Sometimes though, it doesn't go down to 1000 RPMS, sometimes it stays at 2000 and then the car usually starts to overheat. I don't know what to do or where to start to figure this problem out.. I'm think maybe the cat might be clogged? (I'm not really sure, and I don't know if it would cause problems like this..)
Please help me!!!
-Amy-

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1987 Red Thunderbird Turbo Coupe
Been in the family since I was 6 and I've been telling my dad since then that it's my car.
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mods - K&N Cone filter, gutted catalytic, Star Clutch Stage II
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There are a few reasons that can do this, first the TPS could be out of wack, second you may have a vac leak or loose IC hoses. It is also possable to have VAM problems. Your best bet is the TPS. It is mounted on the fire wall side of the throdle body under the air idol controler. ( round thing on side of TB)

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NATO Member
88 TC + a killer driver= one bird that can't be stoped!
2.5 in. side pipe exhaust with no muffler, K&N cone filter, Gillis set to 18 PSI...= the loudest TC knowen to man!It is time to build the Bitch of all 2.3's!!!!!!!

Well, I'm going to go change the spark plugs on the beast today, so I'll check for loose IC hoses..
What exactly do I check the TPS for?

What's the proper way of going about troubleshooting, and adjusting the TPS?

Thanks..
-Amy-

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1987 Red Thunderbird Turbo Coupe
Been in the family since I was 6 and I've been telling my dad since then that it's my car.
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mods - K&N Cone filter, gutted catalytic, Star Clutch Stage II
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It's in the Technical Articles Section right here .

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Mike Walsted - NATO member
1986 5-speed TurboCoupe and 1985 5-speed XR7