Can't find my answer in the manual so... Engine stumbling on acceleration. Thought it might be EGR valve. Pushed on diaphram in idle, speed drops so that's normal. Moves freely. Checked transducer.
Exhaust gas pressure at lower port OK. Vacuum at carb port strong.
No vacuum at EGR port at idle. Weak vacuum at slight acceleration. Vacuum drops away at hard acceleration. Took transducer out to bench. Applied light compressed air to lower port and there's an audible movement. No vacuum at EGR side without pressure at lower port. Reapplied pressure at lower port and air moves through, but not what I would call freely.

Here's the Question: Is the EGR circuit designed to operate in a limited range or should the recirculated gas going into the throttle body ramp up with acceleration and drop off when you slow down? The way it's running now seems to shut off the recirc at idle, allow for a small amount at light acceleration and shut off again with heavy acceleration. If I bypass the transducer and hook the EGR direct to the vacuum line, it roars up and down with nary a stumble but the heat going into the TB doesn't seem normal (plus I don't think they would have put in the transducer if they didn't need it). The cut-away illustration in the book shows two positions for the transducer "at idle" and "under acceleration". I don't get the fact that vacuum passes through the transducer at light acceleration then disappears at heavy acceleration. It looks like a two position device, either open or closed. Am I missing something?