This brick has been very frustrating! (my sister's)
1989 245 manual non-turbo.

from the responses, I've been leaning towards the ECU, but money is tight.

It stalls at about 1800rpm, re-starting when rev's drop, driving or standing still!

I've checked:
AMM
25 amp fuse
knock sensor
oxy sensor
throttle sw.
Fuel pumps
fuel relay
Fuel pressure
plugs wires and cap
temp sensor
air control valve.

I'm not discounting the ECU, but I've found problems with the wiring. The three green wires to the AC drier have been melted and cut! There are no wires connected to the AC control! (grey/red and the green)

...when checking the fuel pressure, the car did NOT stall with #4&6 fuses pulled! I thought it was because the car was full and facing down hill. Until I checked the voltage at the main pump. It's getting 12V without the fuse at the pump, pin 4 of the ECU, pin 5 of the ign control module! Fuse only has the battery 12v lug attached (the #6 fuse is not being used)

The question:
Is there an obvious place that the pump could be getting 12V without the fuse?

Or am I missing something obvious?

Thanks for the input.

Bill