This is my first thread here. I really enjoy Brickboard. I hope they enjoy my tip I gave them.
1991 740 Wagon
Engine runs badly: Engine Shakes, sputters, poor fuel mileage, won't hardly accelerate, an exhaust leak at the 3 bolt flange by manifold adds to the noise level (one stud is sheared off.) It has the BOSCH fuel system.

Here is what i have done so far: Checked codes, at #2 - 111. at #6 - 143. I have ordered the knock sensor for it, but don't have it yet. I checked with the engine running and knock connector removed, the voltage at the 2 pins is 0.0 and .011 VDC. I have checked the pins at both ECUs and they look pristine. When I ohm out the sensor off the car, I get absolutely no resistance, an infinite value. I am not sure if this is right. I tapped on the engine with a hammer while running and the engine didnt seem to change whatsoever. I have changed the fuel filter, spark plugs, pulled off each plug wire, and the engine seemed to run categorically worse, then unplugged fuel injector connector, same effect as the plug wires. Reset the codes numerous times, unplugged the negative batt cable several times, played with the Mass Air Sensor, the engine doesnt change performance at all. Engine does change when I press the button to retrieve the #6 code (not sure if this is normal either) If I unplug the MAP sensor, it dies with a quickness, or if I remove the vacuum line. I removed the timing belt cover and lined up the crank pulley with the 0 degree mark on plastic indicator, then reviewed the CAM pulley dot and it lines up perfect with its plastic indicator behind pulley. The belt looks good and have sufficient tension in my opinion. Before the car developed this problem, it started up fine one day and had no interior electrical and the trans made a horrific sound when placed in PARK, no sound in drive, reverse, etc... Turned car off, unplugged batt and replugged, started up fine, no drips, no runs, no errors, but that was many moons ago. Not sure if it may be somehow related to the problem at hand.
Please Help. I am new to VOLVOs. BTW it has 190,000 and it seems that the previous owner took good care.

Prevost3000