While driving and taking the car out of gear the tach or idle will drop to around 500rpm and go back up to normal. also when I shut the car off and start it right back up it will do that same thing about five times and then idle fine until I give it gas and let go it will drop to 500 rpm's. Help!

Anyone!!!!

What all have you checked so far? Possibly the B.C.D.D. (Boost Control Deceleration Devise)

I have a 60mm throttle body from a 240sx, it doesnt have the BCDD. It just started doing it about three days ago. I've checked all wiring checked EGR valve for operation, looked for vacuum leaks. Is there anything in particular I should be looking for?

Also check the throttle valve switch. Make sure the idle contacts are closed when the throttle is closed.

You know what, I was playing with the throttle valve switch the other day and did not know how to set it because it is from an 84 300zx. While turning it it would make the idle shift but now it does nothing. Looks like that is what I am going for next. Thanks sblake now I just need to find out my electrical problem for the #6 injector. Thanks guys for the help

On these throtttle valve switches (300zx), can you test them the same per FSM for the 280z valve switch?

Don't know much about the later throttle valve switches but when I tried one from the V6, it didn't work properly on my 810 which has the same setup as my Z. By then I think they were referred to as 'throttle position sensor' and perhaps the circuitry in them had changed.

Still having the problem even after a new switch. Help, any suggestions would be great!