Toyota Repair: 2000 Toyota Sennia, toyota sennia, air control valve

Question
2000 Toyota Sennia 219,000 miles new motor @ 80,000 new transmission @ 120,000.
When it's cold or damp/raining it don't like to start and stay running. I have to keep giving it gas until it get's to 2 rpm or it will die. On occasion it will die while moving but only after traveling a no more than 100 yards. I have had conflicting reports on what the problem is. One said Idle control valve was messed up and other one was the Idle sensor. Not sure where to go with that. On a different note or kinda same, I was leaving and van hesitated and didn't want to go. At that point the battery light flashed on and off a few times then the check engine light came on and stayed on.  I took it to Advance to check battery and it tested good. So they hooked it up to read code on engine light, It came back air/fuel sensor bank1,bank2. Not sure of code number, he didn't tell me. I looked it up and saw I have 3 sensors not sure which ones I need. There is so many to choose from, I don't want to get the wrong one, just hopefully the cheaper one. And last problem as they always seem to come in threes.  My ac wasn't cooling so we added a can of coolant and it didn't help. Took it to garage and they put a can in. It seemed to cool a lot better but on our way back from vacation it started making a crazy sound. Had a friend look at it and he thinks the compressor is going out. So not sure what to do.  There are many of those as well. Or is it possible to shorten the belt to bypass a/c until I can have it fixed? Your help would be greatly appreciated. Sorry it's so long and many questions. Thanks

Answer
The idle and stalloing problem is usually caused by a sticking idle air control valve located on the throttle body, it can usually be removed and cleaned or replaced, at the same time the throttle body should be cleaned. In order to tell you which air/fuel sensor should be replaced I need to know the trouble code number, try to go back to advance and tell them you need the code numbers then I can help with that. It's possible the compressor is having a problem, it's hard to say without me connecting a/c gauges to the system to read pressures, A/C problems can be difficult to diagnose so I would recommend the dealer for diagnosis or at least a shop that seems to know what they are doing.