How do you know if this thing is bad or going bad? Just driving down the road at no excessive speed, the engine seems to surge and the car sort of bucks along. No issues at idle or under acceleration.
I thought I read somewhere this switch could be the problem. Is there an article somewhere or referral where I could find out how this switch works and how to test it. Thanks.

http://members.rennlist.com/pbanders/DJetP...rottle%20Switch

I'm having a similar problem. The car runs great except for the occasional stumble at stead speeds. I replaced my TPS board and adjusted it properly and it still stumbles. Not to say that the TPS is not your particular cause. These things are hard to trace.

I'm wondering if my fuel filter may need replacing and I get an occasional fuel starvation. Although at full throttle there is no stumble.

What induction do you have?
If it's dJet:
Check your FI trigger points and FI grounds, especially the ground under the plenum.

we just talked about this a week or so ago.
http://www.914world.com/bbs2/index.php?sho...=108094&hl=

bucking sure sounds like a tps, second thing would be trigger points

Ditto.