Had a fluctuating temp issue so changed the T-stat today. Seems to have solved that issue, but now I get a very slight rough idle when parked. At the same time I also changed the fuel filter, because it was time. It smooths out nicely and runs great when in gear, but I feel a little shimmy at idle that wasnt there before. What could have gone wrong? When I changed the T-stat it leaked some coolant which I then rised off with the hose once I bolted back up. I might have got some water in/on the alternator or other connection. Could then have caused my issue? That was my first thought but it has been hours and I've drive quite a bit and it's still idling a little rough. Or could it somehow be related to the fuel filter change? Any ideas?

 

I wash the engine on mine with a power washer a couple times a year so I wouldn't think it is water related. Any leaks on the fuel filter housing? Is the drain valve completely shut?