the TPS fail for a lot of reasons, mainly polaris chose a junk sensor that is unreliable at best. the stock sled can barely support enough voltage to keep the thing running. now add extra injectors, oil pump, and gauges, your really taxing the charging system. The TPS may have not liked the lower voltage and was causing it to fail.
and if your sled was "blowing belts like crazy" would it not seem advantageous to fix this simple problem and clean your clutches instead of continue to waste money on belts?
Justin is a stand up guy, if you had called him and told him your situation i am sure he would have made it right. Just seems strange to let your season get ruined by some very small and low cost parts which are easy to fix.