One more question: I have ordered a new TPS (and MAF sensor to be safe) and they should arrive soon. When I install the TPS, there's no sort of adjustment needed is there? Just put the new one in the same way the old one came out, plug the wires back in and go for a test drive, right?

 

No adjustment, just don't over tighten the screws, the torque spec is 2.2Nm(1.6 lb.ft.)

 

And the winner is...........Savannah Buzz. I installed a new air filter, MAF and TSP and the Disco runs fine now. I'm pretty sure the TSP was the primary culprit, but decided to order the MAF just in case.

If anyone out there is planning to replace their TSP (or throttle body heater gasket which is prone to leaking), the screws holding them on are 5.5mm. Not 5mm and not 6mm, but 5.5mm and they are not slotted. Otherwise, the job is quite an easy DIY'er.