Mixed Diagnosis on '98 Escort ZX2

I'm sooo confused. My car ran fine except for rough idling when first started last weekend. ONce I put car into drive and started moving it ran fine. I got to work just fine last Monday but when I left work 8 hours later(in the rain and cold) it would try to start but couldn't quite get started. So I had it towed on Tuesday and they told me it just needed a tuneup (or so they thought) So they replaced all spark plugs and wires and did an oil change on it, but that didn't fix the problem and it wouldn't run more than 1 minute. So they told me that it was my head gasket and when they opened the coolant cap on the radiator the coolant exploded out of there even though the fluid was cold. Well they couldn't do head gasket repairs so I had it towed again. The new place told me it wasn't the head gasket and the cam sensor was unplugged and there was water (not coolant) in the 1st cylinder. So they did a flush and fill on the coolant, changed the thermostat and dried out the 1st cylinder and ran it for 30 minutes in the garage and it ran just fine with heat and all. So I went and picked it up last night and drove it around town (since I drive an hour to work) just to make sure it was running OK and it seemed to run just fine but about 20 minutes into in the heater was blowing COLD air, but had been blowing nice and hot air. So I didn't drive it to work last night. I went out this morning(very cold morning) and yet again it was trying to start but just couldn't quite get started. I checked coolant level(fine) and oil (very thick and black, but just got changed about 1 week ago). Any ideas what the problem could be? No one seems to be able to give me any answers. HELP!!!:banghead:

Low oil pressure can cause the occasional stalling in relation to the VCT. I never had this happen on a Zx2 but I had a Toyota Celica that lost just about all of the oil pressure, the oil would turn into mud after about 100 miles. Did anyone check that? As for the random heat....that's possibly unrelated. They may have put in the wrong temp thermostat. I did that and it runs fine in a heated shop but doesn't blow heat when it's cold outside. I really would have to see the car in person. I highly doubt it's a head gasket though. Good Luck...