Hey, I have had a TDI for a while now, and it's started having a few issues.
First one is it has trouble starting warm. The first fault code reading showed faulty glow plugs which were replaced, then when it was read again it came up with no codes. Been recommended a new temperature sender by my trusted mechanic as a second point of action to try. I know injectors can be an issue too, but run several tanks of fuel with injector cleaner through my car, changed the fuel filter every 10,000 miles since I've owned the car (done 35,000 miles in it myself, mostly motorways) and no fault codes have showed up. I was wondering if there's anything else minor I could investigate to solve this issue. It doesn't ever fail to start, just annoying having to sit there for up to 10 seconds getting it to fire up when warm.
Second issue, it randomly idles at 1,100 RPM. I can be sat there in neutral, hand off all controls and it just revs up for seconds or a few minutes sometimes. I'm at a bit of a loss as to what causes this, was thinking it was as issue with the throttle body but my experiences mainly lies with my old 1991 Golf GTI.