OK, so here is the situation...

My sister has a non-turbo 8-valve 1991 740 wagon with approximately 189K miles on the car. It was fairly we maintained and has been a reliable daily driver for some time. Recently, the car developed a problem wherein it is bogging down for periods of time and then suddenly surging back to normal. Oddly enough, if you turn the car off and restart, the problem seems to go away for a minute or so. If you restart and let the car idle, it will start to run rough and bog down in about 30-60 seconds. Now if you slowly rev the engine, the rough idle and the bogging down will also subside for a short amount of time.

So here's what I've done so far:
[ul][*]Replaced the fuel filter[*]Checked and cleaned plugs, wires, cap and rotor.[*]Checked the vacuume lines and they all seem to be in decent shape with air flow.[*]Fuel pump is coming on with the key in the auxilliary position and sounds fine.[*]Checked connections and cleaned the mass air sensor.[*]Cleaned the throttle body.[*]Getting code 1-1-1 (no problems) in port 6, and code 2-2-1 (running lean?) in port 2. [/ul]Any suggestions would be greatly appreciated.

 

There are several things I would look at. Remove the vacuum line to the fuel pressure regulator and see if there is fuel coming out (leaking). Look at the intake connections at the throttle body and see if one if them is either off or loose. Remove the intake duct from the mass air sensor to the throttle body and see if it has a hole. You have to remove it to see because it will crack on the lower side. Let us know what you find.

Dale