Engine code P2125-dealer analysis indicates need.

Engine code P2125-dealer analysis indicates need throttle position sensor (TPS) which requires new throttle position body@1,000. Want to provide following history-in 2010 while driving had sudden lose of normal exceleration & car bucking, stopped and returned to normal soon after, but symptoms returned, dealer replaced pedal position sensor (PPS). Drove fine for just over 1 yr, happened again, although dealer said PPS was fine, I and replaced again because was about to take a trip. Happened again 3 mos later, Nappa replaced gas cap & but in a liquid fuel cleaner, then drove fine for 3 mos. Doing same thing again, dealer says need new TPS. I am leary of dealership services. On line research indicates a throttlebody shouldn't need replacing until over 100K miles. Questions: 1-Could it really just need throttle cleaning by a mechanic? 2-another bottle of liquid cleaner? 3- could the first liquid cleaner have damaged the TPS? 4-when doing a car analysis does the mechanic do a visual inspection of the throttlebody. 4-Or, if it is a hands on manual inspection of the throttlebody, may he have cleaned the gunk & dirt of the throttlebody because now it works fine?

Although I believe the throttlebody is part of the powertrain, I am the 2nd owner so the warranty does'nt cover this. I like the car even with its poor gas mileage, but would like to keep 2-3 yrs longer until more gas efficient SUVs are developed.

One important note: about 3 years ago during normal maint. Servicing, dealership recommended a "injection cleaning". Thinking it was a possible recommendation that wasn't really needed I didn't do it, plus I read that injection cleaning is a ripoff. Should I have done the inj. Cleaning?

On other thing: I'm will be at 60K soon, maintainence says to replace timing belt at 60K, which I will do - do you agree? Also, says should replace spark plugs and coolant. Thank you.