Look at the "sticky" post above this section on 700/800 efi problems. 80% of the time it's wiring not sensor related. Sounds like the dealer may not know what they're doing? The sticky post references a good place to get tbap and tps harness repair kits that may causing be your problem? Plus if dealer didn't check fuel pressure,it's supposed to hold 39 psi.Plus may or may not throw codes if it's a wiring harness short. Look at the wiring from the tps and tbap sensor leading down into the main harness for any bare wires or soft feeling wires that may be shorted internally. Here's the source for harness repair kits if you narrow it down to that. Only The Best