'99 Sputtering Issues

Wifey has a 99 venture. Been acting up last couple months. Until yesterday problem has been alright. Give it the gas now and it just hesitates and sputters and eventually will get up to speed, but kicking the whole way. Did it for about half the day yesterday. This morning headed to work and it was doing the same, getting a little irratated, I punched the gas and since then it hasn't been a problem. CEL is still on, but not flashing. Been started and driven multiple times today with now prob. Had a P0300 a few weeks ago, and pulled the codes again this morning expecting the same. Well, also got a P0170 (O2 Sensor Junk) and a P0170 (System too Lean) on top of the P0300. Going to try the spraying water on the wires tonight to see if that gets me anywhere, but definitely think one of the c packs is gone. Definitely feels like a misfire problem, but don't understand why tromping the gas would have helped any. Any thoughts or possible suggestions? I'll be putting plugs in my GT tonight (YAAAA 2 hr job), so I plan on checking out ye'ole MV while I'm at it. Thanks

Might want to take a look at the fuel pressure regulator. Mine was leaking thats why I changed it, but it does have a vaccum line as well. Maybe that might tie in w/ the pedal mashing.