please help me diagnose these three problems!
 

1. Unstable running engine. When stopped, the RPM needle never stays at one, but goes up and down around it. You can feel and see the engine sort of "rev" itself a little rhythmically. I had my mechanic see it but he said hes gonna have to do a full inspection and wont be able to get to it till next week. He has ruled out a tune up and says it could possibly have something to do with a bad catalytic converter. The idiots at Firestone had told me it was "using reusing old fuel" but I dunno how reliable they can be since they did after wreck it in the first place. So, for those of you experience Supra owners, I was wondering if any of you have had similar problems. Mines an 7GME w/ 108k original miles.

2. I cant get the damn high beams off! This is the second MK3 which I have a problem with. Seems the light swtiches were made so brittle. Is there anyway to have them be sturdy?

3. If the car is moving very slowly (like in heavy traffic) the car gradually heats up, and when I take off again the temp gauge quickly goes down and then becomes unstable. Thermostat change?

I will be using it as my commter car for the next 3-4 days, about a total of 10 miles a day. Am I safe?

one last question: 7MGE uses 159 or 169 teeth?

1. Vacuum leak and/or bad sensor?

2. Yes, the combination switches suck. Not sure how to undo constant high beam.

3. Check your coolant level. If it begins to over heat, run your heater.

4. Not sure what you're asking with "teeth"?

5. The car seems OK to drive for 3-4 days, but sometimes you just can't tell.

Correction
 

The "teeth" refer to the timing belt. I forgot to put that.

bullz eye you hit the bulls eye ;)

vacuum leak.. get carby cleaner or whatever you call it over there and spray it around all your air pipes.. when your idle changes rpm theres your leak

never had the "stuck on full beam" before so i guess the switches have dirty connections.. try replacing it

never counted the teeth on the timing belt before so can't answer that one

do you have a light on the far left on? looks like a birdcage, roman building etc?
check your coolant level

im thinking your cooling problem is the fan clutch, is the fan real easy to turn when the car is hot?

Check your TPS for the unstable idle speed. Happened in my pickup and it solved the problem.

Maybe get your radiator pressure tested and cleaned. YOu aren't having to give it coolant periodically are you?

As long as it's not overheating at speed I'd say it's safe to drive.

You know for the teeth of the timing belt, I thought there was only one belt for the 7M motor/s...?
On my 7M-GTE motor, I have a 159 tooth timing belt.
If someone can confirm they are the same as the N/A models, then it would be 159.

I would be interested in knowing if N/A's have different belts than Turbos.



Edit: I would be very cautious of a heating problem. Overheating can crack blocks (seen it happen on a 7M) and can warp the head too.

If you are on a road and you have a temp spike, it may be so fast and you may not even notice, while the needle could be beyond where the gauge reads or intended to even measure.

No water, no gauge reading
 

This reminds me to let you know. BEWARE !!!

The temp sending unit is located on the thermostat housing. It is one of the highest points on the engine with coolant. If your coolant level drops below the sender, your gauge will not raise up, because it needs coolant touching it to send an accurate signal to the gauge.

Your gauge will usually drop down a bit, and make you think your engine is actually running cooler.

So learn your car, and know where your gauge normally operates at. Look at it often when you drive.

And make sure your radiator cap holds 13lbs, they do get weak as the years go by. ( I almost lost a freshly rebuilt motor in my '65 Mustang due to a cap that was supposed to be 14lbs, but only held 7lbs).

All of the above happened to the Mustang.