A while back I posted a thread in regards to throttle body interchange as it had a whistle at 1/3 throttle and not a vacuum leak. Per Agrazela the 98 TB had a wierd lip at the bottom of the throttle plate and he had the same noise. I got a 99 TB free for parts and I changed out the throttle plate on the 98 TB with 99 TB and the whistle is now gone. The 98 TB does have a wierd lip on the bottom. The 99 TB plate is similar but has grooves in the bottom and no small lip. This was a very annoying whistle and sure made one think there was a vacuum leak.Yes I did put locktite on the TB plate screws. No codes and it drives real good. Thank you to Agrazela & Dan much for the input as I have been fighting that one for a year.

Glad you got that taken care of. What'* your plans for the old TB?

The guys at GM told use what I needed and just return the rest. Small town help from the Medford guys.