I'm Feeling A Bit Sensortive

Sunday - One week ago today:
My wife calls me (I was at home) from church and tells me the car won't start.  Ignition won't turn over at all, car clock is dead.  Surmised that the battery's dead.  Can't boost it because she can't (nor my father in law) get the hood open.  A couple of years ago, the plastic hood release latch next to the driver's side seat broke, and it's been more and more frustrating getting the hood opened, to the point in the past couple of weeks, where it's almost impossible.  In fact, I think I am the one who knows how to open the hood.
So, her parents give her a ride home from church and take me in to see if I can open the hood and start the car.  Getting the hood open involves cutting the carpet on the floor and stipping the plastic cording around the release wire.  After about ten minutes, I get the hood open, put booster cables on the car and it starts immediately.  Drive to my in-laws and borrow their battery charger.  The charger tells me that the battery is basically fully-charged.  Hmmm, I think, doesn't sound like a dead battery problem.  Assume, though, that it is.
Monday:
Car starts no problem in the morning.  At noon, I drive to pick up DaveS for lunch.  Get in the car, and ignition won't turn over.  Swear a bit and get Dave to get his car and boost it.  Starts no problem.  I decide to take it to our mechanic.  I do, and tell him the problem.  We both agree that a new battery will likely solve the problem.  So, on Monday, the car gets a new battery.  Driving home on Monday evening, after picking up the car from the garage, it stalls at every intersection I come to.  I swear a bit at this new development.
Tuesday:
Take the car back to the mechanic, who says he'll look into it.  I leave the car there all day.  Pick up the car (no charge for the second look) after mechanic's gone home, and the same problem.  Car stalls at every intersection.  Plus it starts to stall if I'm driving down the road without my foot on the gas.  Zen training keeps me from swearing much.  Plus I was pretty much expecting it to be not solved.
Wednesday:
Take the car back to the mechanic.  Says he'll look at it again, but admits he's puzzled. If he can't solve it, he suggests I take it to a place where they can run computer diagnoses on it.  I come back around noon and he says he was talking to someone at Dave's Auto Electric.  He suggested that the computer needs to reset, and to do that, the car needs to be taken on a good long drive (he suggested 45 minutes).  Not allowing myself to believe this would work, I nonetheless go for a lunch-time drive around Brackley, the north shore, Tracedie, etc.  Car is driving better, but once I get back into town, it begins to stall again.  No swearing at all, because I knew the outcome and was prepared for it.
Thursday:
Call early in the morning to Dave's Auto Electric (the place our mechanic suggested we go), but they say they're booked up on Thursday but would try to squeeze us in on Friday.  Because my wife and I had places we needed to go on Thursday and Friday, and were totally frustrated by driving a car that continually stalls, my father graciously offered to loan us his car.  He says it sounds like a faulty sensor.  I agree and expect that's what Dave's Auto Electric will find. We leave our car at my parents.
Friday:
Drop car off at Dave's Auto Electric, but because my wife and I are both busy all day, I ask my father if he'd be the contact.  Mid-afternoon, he goes to pick up the car.  They've installed a new alternator (that and labour = 225 dollars), they take it for a test drive and it's still stalling.  They suggest to my father that we take it for a good drive to reset the computer.  There is confusion from them why they were not able to check the sensors.  I am totally deflated at this point and do not press the issue, so  we take the car for a drive.  No change. Still stalling.
Saturday:
Drive the car into town to do the things I had scheduled.  Car stalls continually.
Sunday:
My wife drives the car to church.  I didn't ask her, but I assume it's continually stalling.
Monday (the day after today):
I don't know whether to go back to Dave's Auto Electric, or to take the car to a certified GM Chevy dealership and let them gouge me with their exorbanent labour charges.  Of if I'll be able to make an appointment at either or any place.

If the car doesn't get fixed at the next place we take it, I'll be officially pissed off.