I pulled off the vacuum line from the regulator, which does seem a little brittle, but no fuel there. Here's what the mechanic wrote that he did:
"Removed and checked all spark plugs and verified rich condition. Checked fuel pressure, OK in spec. Adjusted mass air flow sensor, no improvement. Installed mass sensor, no improvement. Checked O2 sensor, OK. Operation normal reading for rich warm engine templ. Tested coolant temp sensor, OK spec. Checked injector pulse, OK spec. Recommend checking all power and ground input and output from control unit to verify faulty control unit or wiring."
I checked all of the terminals at the control unit and the only thing I found that was not the way Bentely says it should be is that there is no continuity between #12 and ground when the throttle is all the way open. Also no continuity at the throttle switch when the throttle is open, which is why I was wondering if this could be the problem? I don't quite understand why a problem when the throttle is wide open could make the car idle badly, but then the fuel system is the area of the car that I feel least familiar with.
Sorry for the long post, but my husband is ready to junk the car and I am thinking that this has to be a relatively minor problem if I can just find what it is. Karin