I have a similar problem on a 1989 F-150/ 5.0 with 5 speed. Intermittently the truck will stall when coming to a stop. It appears the idle hunts up and down or just goes too low and truck dies. I have swapped O2 sensor, plugs and cap/rotor. Interestingly enough when I unplug the MAP sensor the truck runs like crap initially, then when warm it runs fine and hasn't stalled. I bought a new MAP sensor and it still stalls. I have replaced the IAC valve and was wondering if the ground could be bad. It appears that the IAC and injectors and just about every other sensor gets its ground thru the EEC. I found 864 ohms to ground and was wondering if anyone else has found or tried this. Thats seems like a lot of resistance to me, but when the MAP sensor is unplugged the truck runs find after warmup. I figured the truck probably would not run well if this was not the designed resistance to ground. The catalytic converter has never been replaced but then we still get back to when the MAP sensor is unplugged it runs fine except Idle speed is slightly higher at 1000 rpm. Any guru's have any ideas? By the way, the filters have been replaced.