'96 SW2 sticky footfeed - but only when running?

Hi all, I have a '96 SW2 wagon that has developed a funny sort of sticky
accelerator pedal - it has to be sort of 'pushed loose' each time (there's a
quiet 'thump') and this makes every takeoff a somewhat jackrabbit start.
It's as if the pedal is catching on a wire or something at the top of its
travel, or adheres to something sticky at the top. I think it gets slightly
worse as the day goes by - sometimes it's better, sometimes it's worse. The
kicker is, when I shut the motor off, the problem goes away instantly and
completely. Comes back when I start the motor.

I was going to douse the area with WD-40 or some such until I noticed the
problem depended on the engine running.

It may not be hurting things yet, but it's very irritating. Anyone have
any ideas? Thanks - cmb

 

Clean the throttle body (butterfly valve on the air intake) with throttle
body cleaner.

Steve