Frustrating problem with 940 dying randomly. Only dies shortly (1-3 miles) from a dead start. This is summer time in Tennessee. 90 degrees. Car will restart after a few minute rest. Like the old time vapor lock.

On diagnostic LED I get 223 (signal missing from idle valve error) and 132 low voltage error. I have removed and cleaned idle valve which looked very clean and seemed to be operating smoothly. Cleaned contacts. I replaced pressure sensor. I ran a can of injector cleaner through and throtle body looks good (sprayed cleaner anyway). Fuel pump was replaced somewhere in last 10k miles (used car, not totally sure of date) and fuel filter looks brand new...still shiny..so I suspect stlling problem is persstient. I have looked at ground wires, checked battery voltage at load, cleaned terminals, etc. looked at vacum lines, checked most of the codes on the computer identified in Chiltons manual (Pump relay indicates good).
Clear the codes and then after it dies (randomly) I get these same two codes.

Where to look next? What could be causing this combination of errors. Perhaps coicidnetally the spedo has become erratic. Replaced sensor with junkyard part and didn't get any better, maybe worse. Could these be related?
Any and all help greatly appreciated.