won't idle

My 99 Passat v6 won't idle correctly. It has caused my check engine light to come on. When the car is slowing down from normal driving, you can feel the automatic transmission shifting through the gears back down to first. Right when it goes into 2nd or first the RPM drop way low to about 300 and sometimes the car stalls. It will start right back up and sometimes stall again. When the car is still, the idle will float going up and down between 400 and 700 RPM. VW wants $72 just to run a diagnostic and no other place says their computer can talk to a VW.

Does anyone know if there is a company that has a computer that can talk to a VW. (where's R2D2 when you need him!)

Has anyone had this problem with theirs and had it fixed. I have chaged the plugs, air filter, fuel filter. I was told it may be the Air idle motor, but I am not sure where that is on the car.
Thanks,

RL

I've seen alot of complaints similar to yours, search the threads. Most relate to the throttle control valve & carbon deposits inside it. Most people say taking off the air intake boot and cleaning out the deposits corrected the problem.

do you mean the oil deposits inside the air intake boot that leads to the carb? the boot that runs from the air filter to the carb?

Clean the inside of the throttle body (there is no carburetor) after removing the air boot. If that doesn't work there is a company that makes a VAG scanner simulator for PC's:

http://www.ross-tech.com/index.html

It is only a scanner, you will need repair info also. In my opinion Bentley has the best (in paper & CD-ROM):

http://www.bentleypublishers.com/product.htm?code=VP04&subject=20