93000 isn't really that much for a 3800. Has your Service Engine light come on?
If you suspect a bad sensor, cleaning them with Electrical contact cleaner might help.
Have you tried using Seafoam or GM Top Engine treatment to clean the upper engine? It will get rid of carbon buildups. FYI, in the TB, the throttle plate may get a build up of carbon around the outside bore which can affect the TPS. I took my TB right off to clean it and noticed there was quite a bit of carbon there. FWIW, here are a couple of pics showing before/after. (the engine did run nice after the cleanup)
Your TB may be slightly different, but not much. Here'* some basic stuff for you. Note: The MAF, IAC and TPS have only 2 screws holding them in. The IAC and TPS have rubber O ring seals. Don't lose them or crush them putting them back in.
Now here'* the TB apart. The small 'groove' with the clean look at the top of the pic is the IAC pintle slot. It got cleaned even better once TB was off the car. BTW, if you do this, you will have to drain some antifreeze. The 3 nuts that hold the TB in place are fairly easy to get to, and the TB seal can usually be reused. It'* only 8 bucks at NAPA if you decide to replace it.
Here'* what it cleans up to: