Throttle Position Sensor issue

The description sounds more like the throttle body or communication has an issue rather than the TPS. The other item would be the APPS or Accelerator pedal position sensor AKA the gas pedal. Those however don't normally fail and then reset as they are nothing more than a pair of potentiometers. They also normally don't fail without setting a few codes. There are multiple items that control the throttle and from the description it sounds like a communication network issue because it did reset. Hard failures usually don't. Is this car stock? No added aftermarket items like remote start or similar, those have been known to cause problems on the network. The first thing to do would be to use a scan tool and scan for any codes. Those would give an idea of where to start looking. From there it depends on the codes and what they show.

Stock makes it easier. I've had cars come in with stereos, remote start and other items added on. The problem with many modern vehicles is that those need to be installed very carefully and need to be high quality or they cause problems. Makes it difficult to track down why a car doesn't start when things like that happen.
Price wise it will depend a lot on what they find and their labor rates. Around here the testing and diagnostics would take about an hour if nothing pops up quick. The throttle body is part# AT4Z-9E926-B and it takes about an hour to change. The pedal sensor is part # CR3Z9F836B and takes roughly a half hour to change. Price wise those are easy to look up.
We generally don't refer people to shops, simply because we get questions from around the world and before I would tell anyone where to go I'd need to visit the shop and trust them. However it depends on what the customer here wants to do. Normally we will give an idea of what the first steps are, then if they wish we can guide them through testing. However that can be difficult to do depending on the problem. For some things like bad lighting something like a test light and where to test will work. For others you need a full fledged scan tool with full controls, an oscilloscope and the mind of a NASA engineer to trace down the failure and the cause. Most are in between those.
For your issue a scan tool to read all of the codes is the first step. Then look at the codes and see if there is a common reason for them or a TSB about this, then test some more and determine if it's a failed part or something else. Some people wish to do it themselves, others just want an idea of what it is and what they should pay and still others want to know why the shop charged them $1000.00 to "Replace a part that I can get on Ebay for 20 bucks"