My car was hot, about 205 degrees. When I started it up the idle was rough, my rpm was around 1k. I heard my CAT rattling, not like somethings loose inside rattle, but the whole CAT itself was rattle/shaking a bit, then when I put the car in reverse and it jerks and when I put it into drive. Its like my idle is too high, which is probably a TB problem right?

I thought I felt some heat underneath the car right by the my drivers seat, but it was prolly the wind blowing the heat from my tail pipe or is it my CAT?

If you feel a jerk going into gear.....

Check motor mounts/tranny mounts??

This may have loosened the CAT connection, making it rattle.

Id also check the cooling system, as 205 degrees might be a little hot, especially with the plastic UIM. Change coolant/thermostat lately??

Bob

I only feel the jerk when my I feel my car Idling high. You know how, just start up your car for the first time of the day and you let it idle, but my doesn't idle down. my tps sensor is .55V shouldn't it be lower?

just for my own curiousity. Unplug the IAC and see if the car will start and idle. If so, pull it and clean it. Try another one that'* known good if you can(free ones are best ). Also make sure that the throttle plate is closing entirely. The throttle/cruise control cable bracket thignee if the plate isn't closed. Vac leaks also come to mind. Carb cleaner sprayed around the area will tell you.

As others have mentioned, most likely this is not a TB problem, but a bad cat.

Test and let us know the results.

We're not going to continue this in two topics. I choose for you to continue in the other one.