Last weekend i was driving home from Vermont and all of a sudden my truck felt like it was running a cylinder short. I stopped and checked all that i could on the side of the road and had to continue my drive home. The next day I filled her up with fresh gas just in case the gas I had bought in Vermont was bad. Still stumbling so I replaced the plugs, rotor, distributor cap and PC valve. One of the plugs was badly fouled this seemed to fix the problem but the next day on the way to work it started happening again not as badly as before but still missing a lot mostly when its working going up hills. Additionally this happened at all RPMs and only really once the car warms up and goes into closed loop mode I assume. Yesterday I checked the timing it was closer to 20 degrees so i backed it down to about 15-17 since it seems to jump around a little. This helped on the drive home but it was still stumbling every once and a while going up hills. When I got home I tried adjusting the timing further to like 14-15. On my way to work today it was still stumbling maybe a little worse than on my way home yesterday. My fear is that I skipped a tooth on my timing belt but I'm not sure. I have checked all of the vacuum lines and the air filter is clean. And there are no codes (just 55) on the ecu right now.
Sorry for the long post I want to give you guys all of the details. If anyone has any ideas of what to try next that would be greatly appreciated she's my daily so I really don't want to have to take her to the shop.