Smurfturd

This will be my first thread on this forum so bear with me. I have a 2001 A4 2.8 V6 with 132k miles on it. I had a charging issue so I swapped the alternator and while I was at it I decided to change the timing belt and water pump.

I have everything back together and fluids refilled. The charging issue seems to be fixed but now at idle the RPM steadily bounces between 1k and 500 RPM. If I give it gas it will stay wherever I put it. My questions are:

1. Could I have messed up the timing somehow? (no odd noises or other evidence of sheared valves)

2. If not, then is there a commonly forgotten sensor or hose that I could have missed?

Thanks in advance for any help. I'm really worried about the timing.