About a month ago, I replaced my valve cover gasket. A few weeks before that, I replaced my alternator and battery. A couple weeks ago my turbo blew (not sure if it's seized or what the problem is).
So that's my car in a nut-shell. Yestarday, the wonderful day that we had snow, I drove to work and noticed something was different. I had no heat until 10 minutes after I started my car, and even then, the heat was coming on and off as it liked. Thinking nothing of it, I proceeded to work for the day and put it in the back of my mind.
when I left work and started my car, I noticed it was revving to 1800, going to 2000 and coming back down. Obviously, I thought this was strange, and thought about my idle set screw. It was at the top of the hole it sits in and so I screwed it down to its place. That seemed to fix the idling.
Today, on my way out, I noticed my idle was weird. Not the same as Saturday, but just funny. It was revving way too high, and so I proceeded to adjust the set screw. Now, the rev's are either too high, or too low and the car wants to stall.
I also, still have no heat.
My normal operating temperature is dead centre of the gauge, and it's rising and falling sporatically.
Any ideas? I know it's a long story, so thank you for looking anyways.

No heat = thermostat stuck open.

I theorize that it could affect your idle. The fast idle air valve (FIAV) is normally open letting more air past the throttle plate to give you a higher idle on start-up. As the coolant heats up a wax pellet melts and closes the valve. If your thermostat is stuck open and your coolant never gets hot enough, I suppose the FIAV could be stuck open (at least for the start of your driving).

Solomon,

I just started getting a fast-slow-fast-slow idle that cycles once per second (fast-slow in one second), continuously. When you adjust your idle screw (BISS), did you ground the appropriate connectors, or just turn the screw? I tried doing it the "right" way, and it just caused a wisp of smoke to come out of my coilpack, which is now also throwing a code from the ECU. !^%$@%!$@%!@

No heat may also mean no coolant.

Thanks Steve,
I have no coolant. I'll have to top it up in the morning and see hopefully, that's all it is.

Your water pump {like mine} might be dieing. Dont be lettin that thing idle w/o someone watchin the guages or you'll be left with a melted motor. Mine seems to get heat when your on the throttle and it stays cool when air is going through the rad but sitting is a different story. It'll take alot of coolant...doesnt mean the cylinders arent submerged though...welcome to cooling problems Ive done the rad, the thermostat, the rad cap and the water pump is next...{and last}

Wow, I'd expect the low coolant light to go on if there were so little coolant that none gets to the TB and heater core!

Or maybe the carousel (or whatever YOU like to call it) actually was on...?

Also check simple things like your belts. Are they tight enough. Maybe they are loose cause the belt to slip a bit at idle and not driving the water pump. That would cause you to have no heat.

When the low coolant light actually works (if it gets gummed up, sometimes it will "stick") it can only tell you if you have coolant in your overflow bottle.

Unfotunately, now you need to find out why there was coolant in your overflow bottle (unless the swich is "stuck") and none in your engine.

My coolant was definately empty. Took almost a whole bottle to fill it back up. The biggest thing is "why was it empty?". That's something I'll have to look into. I'm guessing my coolant light sensor isn't working and that I'll probably have to replace it upon my rebuild.
That's the only reason I'm trying not to do any more things. It's funny though; whenever we need to save money for something that might fix our problem, we have to spend it on that problem before hand otherwise the car could blow.
Thanks for everyones input, I'll definately be thinking about it in future.

Ok.
Thanks for everyones help.
So we've determined that I'm leaking coolant. Now I've gotta find out where. I can't get into a shop until next week, but I noticed something that I never thought of.
Attached to the overflow tank, there are two hoses. One that goes into the overflow tank from the system, and one that trails off into nothingness. I checked my books and couldn't find where this leads to. Is it supposed to just hang over the side and do nothing? Does it go into another place? Do you think this is a possible culprit, and would just pinching the end help?

That hose is supposed to hang over the side. It's how excess coolant escapes.

Was there any coolant in the overflow bottle, or was it empty as well?

you didn't FILL up the overflow, right?

I figured that extra hose was to let excess coolant out. When I was bone dry(almost anyways) on the coolant, I opened the cap and filled that up, as well as the overflow tank to it's proper places, in fact, a bit too much.
I thought there could be an easy fix, but it maybe be something big. Maybe it's a small leak and some stopleak will work.