Dost take a deep breath and now you are the one who will determine if you are going to spend 25k + on these mechanics or spend some time figuring out the problem.
take it Step by step. Google following for your car
Step 1. Check TPS for its correct values
Step 2. Check for Vacuum Leaks
Step 3. Clean IACV
By the way You can get TPS for 1000 or less even you can have throttle body with sensors for 3500 but first do above