I've been playing a lot of doctor with my 960 Auto lately. I started noticing that the car was trembling at idle because it is dropping so low when I am at stop lights or in PARK. It does this regardless of gear position so I don't believe it to be transmission related. The car starts up just fine and runs okay, but has no punch. So I initially did a check of the coil packs and found that Cylinder #2 was not firing. I tried swapping the #1 and #2 coil packs and found that the problem didn't follow so that eliminated the #2 coil pack. Then I did some research and found out about Dave Barton's Volvo site and I ordered a new ignition coil harness and installed it because mine looked really crappy along with a new ignition module power amplifier for the 2,4,6 cylinders and changed the spark plugs and cleaned the Throttle Position Sensor. This seemed to get all 6 plugs firing again because I verified them with the spark plugs out and grounded against the block to visually see spark jumping across the plug gaps. There's still no change to the problem though.

Today I checked the compression and all the cylinders look to have good squeeze (164 / 180 / 175 / 190 / 175 / 180). The other thing I did was remove the hold down bolts out for the coil packs and pulled them off the spark plugs one at a time while the car was running to listen for idle drop. Cylinder #3 and #4 are not currently making any change which would explain the lack of punch. There's definitely spark on those cylinders and compression. I'm thinking about looking at the fuel injectors at this point, but I want to try and gain some insight from everyone on the forum. I also tested the fuel pressure at the rail and that seems to be in spec at 42 PSI