I picked up a 1987 245 beater with a B230F engine recently that the owner sold due to a rough idle. Odometer shows 106K but does not work. By the wear and tear I guessing mileage is in the 200's

The car starts with a little bit of fuss, drives smoothly down the road, but seems to be low on power and sounds like one cylinder is firing intermittently at idle, enough to shake the engine in the motor mounts. All cylinders seem to be firing fine driving down the road.

The previous owner threw a lot of parts at the problem such as wires, cap, O2 sensor with no success.

Not knowing the car, I started with a compression check. Cylinders 1,2, and 4 registered about 210 psi, but #3 only registered 150 psi. Squirting a little 30W oil in #3 brought the compression up to about 180 psi.

Spark plugs were dry and light tan, even on #3, which was just slightly darker than the rest.

I checked the valve clearances and all were within checking spec except #3 (the one with low compression) exhaust which was very tight at 0.004" (warm engine)

Checking the timing, I found that at idle, the timing was all the way to the right of the markings (10 ATC?) instead of 12 BTC. Raising the rpm caused the centrifugal advance to move the timing well to the left of the markings. Removing the hose to the vacuum advance on the ignition control module makes no difference at idle, but does change the timing at 1,500 rpm (book suggested check point)

The distributor is stuck and will not rotate to adjust, even with the bolt all the way out and vice grips on the housing. I have it soaking in WD40.

The throttle microswitch clicks when I move the throttle but I have not checked it for continuity.

I am guessing that the timing issue is the timing belt and the low compression is the #3 exhaust valve clearance being too tight, but that may just be wishful thinking. Any thoughts out there on things I may be overlooking? I hate to throw good money after bad. I am especially concerned that #3 exhaust valve being off 0.012" is sinking into the sunset.

My plan is to replace the timing belt, change the shim on #3 exhaust valve and get the distributor to move.

Thanks in advance for your thoughts and suggestions.