Does anyone know why a 1999 VW beetle will idle high then low after it warms up? How do i fix this problem?

The reason the car will idle high is it's cold and then low after it's warmer is to keep the engine from stalling. it acts as a choke system almost. and after a minute or so rev the engine once and it should drop to low idle. if not wait a little longer. as for the pulsating it's not fixable to my knowledge. one thing to do is fill up on premium gas once or twice a year. the higher octane in the fuel will help clean it out and if it's a diesel I'm not sure what to do.

good luck

It sounds like the fan to cool the car goes on when it needs to cool and the computer is doing it. On and off and on and off. Is the air conditioning on if it is that is the reason. It may be normal. Now if it is excessive, take it in to a VW dealer and ask if there is a recall or a service bulletin for your 1999 on idle problems.

Mine (2002 VW Cabrio 2.0 motor, auto trans) is doing the same: take it to a shop that can use a scanner to read the codes. I know mine has some injector issues, and am going to get it worked on next week. Good luck!

any check engine lites? possible vacuum leaks,carbon on the back of the throttle plate,computer is" hunting"

may have an engine coolant sensor starting to get worn out.

i agree with the old guy.

Duh! It's supposed to do that.