On August 27th I posted a reply message to MJAMGB on rebuilding the B-20 F/E. I never heard back because there were 16 replies and I don't think he pulled up the site after posting his response. At any rate, this was my post, and anybody out there who can give me an explanation, I would truly be grateful. Here is the post I sent to MJAMG.

MJAMGB--read all the posts on rebuilding the B-20 and have a problem that I hope you might be able to answer. I
have a 1973 145 wagon that had the low compression F head in it. Wanting to upgrade, I installed an F head that had
been milled down to E head specs. I'm not very knowledgeable on rebuilding, and never knew, until I read your post,
that the surface of the head had been hardened. Several months after I installed the "E" head, I began to experience an erratic
idle (this car has the D-Jetronic system on it, not carburetor). At cold start the car would idle at around 1000, as it
should, then cut back to 750 as it should, but then sometime soon thereafter, the idle would suddenly drop dramatically to around
150, barely able to sustain itself. Go into a store, shop around a bit, come back out, start it, idle would be back up to
750. But a few minutes later it would often drop back down to 150. And so it would go, up and down. I tore my hair on that injection system,
replacing absolutely everything, from the pressure regulator to the coolant temp sensor (but not air) , but nothing ever cured that erratic
idle. The shop that did the milling on the head ripped me off, putting in valves they said would handle unleaded gas
(they didn't, they seized, but fortunately came unstuck and thereafter I added a lead additive), milled out a divider
between the intake and exhaust valves, saying it would up the horsepower, etc. I'm thinking of restoring this car back
to specs, but I would like to know if the milled F head and the erratic idle are in some way connected, i.e. warping or
whatever. If the head were warping after it warmed up letting in air and thus off balancing the system, wouldn't this throw coolant into the oil instead of air which would be visible as frothy white oil? When I replaced the head I also replaced all the injection O-rings, so I don't think any air is getting in that way, but I could be wrong. I don't think air past an injector into one cylinder though would account for this dramatic change in idle. I am truly at a loss as to the problem. Any possible explanations from anybody would be most welcome. Dick