2000 VW Jetta P1255, P0134pd, P0302pd

2000 VW Jetta 4cl GLS. 113,000 miles.

I've noticed that my car has a very rough idle as soon as I start the car. It stops after I feed gas and move the car a few feet. The vibrations only happen on a, for the most part, cold start. Check engine light came on not long after the vibrations started.

My 3 codes are:
P1255: Engine coolant Temperature sensor short to ground
P0134pd: O2 sensor circuit no activity detected bank 1 sensor 1
P0302pd: Cylinder 2 minsfire detected

Recent history:
I bent all 4 valves a month ago and had them rebuilt.
I also have:
New mass airflow sensor, ignition coil, ignition wires, spark plugs, and a new timing belt and tensioner (bad installation, was the source of bent the valves)

Whats going on? What do I need to do?

Thanks for any help you can give.
-Mike

I would start by changing the coolant temp sensor. Pretty good chance thats why your having a rough idle at start up. The PCM uses the coolant temp sensor input to adjust the fuel mixture when the engine is in open loop. When the engine goes into closed loop or is at operating temperature it uses input from the 02 sensors the adjust fuel mixture. Start by changing the coolant temp sensor, I think they cost about $20 dollars at dealer.

I'd check the circuit to the sensor first!

first off which motor 1.8 or 2.0?
vw has had for many years major problems with temp sensers. if it's a black one replace it with the newer blue one. same with the front o2 senser. they had a recall that included a needed reflash of the pcm on the 2.0 and replaceing of the front o2 senser. the 1.8 is also prone to bad front o2 sensers. the miss fire on number 2. could be a bad coil pack, bad wire. or plug. depending onthe motor i.d. this motor dosen't like any plug other then the oem brand for some crazy reason. and many after market plugs do not run properly in it when they are cold, even thou they shouldn't they act that way. they do.
also you need to check for vacume leaks at all the hoses. vw used some very poor grade of hose for many years and only in the pasy few started useing a more heat proof hose made of high temp silicon.