2000 T & C Spuddering, Lurching and Stalling

I have a 2000 Chrysler T & C with 178,000. Ran like a champ until a few weeks ago.

Started spuddering and lurching when I was trying to accelerate, then it would suddenly accelerate but then spudder and lurch again, eventually it stalled out. Was able to get it cranked and almost home before it did the same thing again. Eventually got it home, but when I tried to get it to the shop, it did the same thing, stalled, and then wouldn't crank (engine would turn, but wouldn't crank). Had it towed to the shop where it cranked fine. No check engine lights, nothing appeared on their monitors, and they kept it for a day, driving it around but it never did the same thing. I took it home, but noticed it was driving terrible (no power... very hesitant).

Few days ago it started all over. Towed it to the shop where it DID do the crazies with them, but still no check engine light. They said it might be a crankshaft sensor (I believe that's what they said) but then ruled that out. Said it might be the "cluster", but then they took it out and the van still did the same behavior, so they put it back in. Eventually they said they got a read out on the O2 sensor near the catalytic converter and replaced it. They couldn't guarantee it fixed the spuddering/lurching/stalling problem since no read outs ever pointed them to a specific prob other than the O2 sensor.

It drove GREAT... O2 sensor def needed replacing. Drove great over the weekend, but last night it stranded my family and I... started the spuddering all over again, couldn't really get it to go and barely got it into a parking lot. Had it towed to my house and now I just don't know what to do. I don't even know in what direction to start.

The way it was acting like last night seemed like a loose plug wire, but that all looks fine - I've checked it. Have a Haynes book for it and don't mind doing some of the work, but don't know where to begin.

Thanks for reading this long, sordid tale!