1998 Ford taurus.....multipal problems

ok i have a list of problems, some maybe caused by the same thing.

1) when idling in park it will stay around 800-900 rpms ( normal ) then after like 10 seconds the rpms will start to drop to like 400-500 rpm, the car will strugle for a sec then pop back up to like 1000 rpm. then it will repeats the same thing over and over again.

2) Every once and awhile while in park the engine will start to rev higher and higher and will not stop till i turn it off.

3) some times when i get out of the car the inside lights will stay on, sometimes for hours.

4)I also need to know how to replace the thermostate.......

It seems like i may have a few sensors that are bad, but im not sure, and which ones?

I think this is all, there is prolly more but i cant remember right now..

If someone could help me with these things that would be great..

Thanks alot!

Blake

oh ya i forgot to say, my car has 120,000 miles

The engine idle will fluctuate from an intake leak/or vacuum leak, or from a faulty idle air control solenoid (IAC). The IAC has voltage supplied to it when the key is on, so when the key is off it is reseated by a spring, this may explain the second concern you had. The interior lights are turned on by your door ajar switch(s). If the door latches haven't been lubricated regularly then they will stick. This will keep your light on. Spray some WD-40 or other lubricant into the door latches and see if helps. The thermostat is in a housing on the drivers side of the engine. Follow the upper rad hose from the rad to the engine. At the end where the rad hose meets the engine is where the thermostat is. The housing is somewhat round and should have two or three bolts attaching it to the engine. Why do you need to know? Do you have a heating problem? :sunglasse

Cuz i am having problems with my heat, and everyone i talked to asked if i had replaced it yet...sooo...im going to

anyone know about how much it would cost to get my tranny rebuilt?

Ok when your motor starts it revs around a grand till the motor warms up. Then it will drop to about 550rpm that is idle. That is also normal. Now if your rpm's after that are not constant then (in most cases) you either have a vacume leak or your throttle body bore could be really dirty. Which is not all that likely on a ford. What shape is your airfilter in?

The problem that you have with your RPM's jumping constantly could have to do with a low level of freon. I had a similar problem that occured when my A/C was on. If it still happens when the A/C is off then you've got bigger problems that i can't help with. Good Luck.

A sensor out will turn your "check engine" light on. Those are relatively easy to track down.
ALMOST ALWAYS when a thermostat goes bad it will lock open and the car will be slow to warm up. Never saw an overheat problem caused by a bad thermostat, but of course anything can happen. More likely you have radiator blockage, either on the outside or inside, try a good radiator flush first. The suggestion that you may have a vacuum leak is a good one. You need a good trouble shooter to take a look/listen to it! If you drive up to the dealership he will charge you about $3500 for a transaxle rebuild or exchange.