Suggestions in no order ...

Dexron has a better solvent effect than automatic transmission fluid "Type F".

I'm uncertain what fluid the AW-7x series uses.

I've not heard of soaking injectors in transmission fluid as a solvent. What you must avoid is any foreign, solid particle getting into the injector intake. Else, you may induce performance fault in that fuel injector.

You may want to try a fuel injector cleaner service, if indeed the injectors are clogged. Ask them how to safely handle the injectors. Injectors must remain sanitary when serving them.

Also, you have the OBD-1 code check on your 1991 700 series. See (http://www.brickboard.com/FAQ/700-900/EngineOBDCodes.htm). You may have faults.

Your cold compression figures are at quite a variance in cylinders 1 and 2 versus 3 and 4. I'll guess you performed your cold compression test with all sparks plugs out and a fully charged battery?

Indeed, try a squirt of engine oil in each. A healthy squirt, and repeat the cold compression test. If you have a serious rise in values, that fade after two or three more compression test attempts, it is the rings that are at fault. If the values persist or rise only slightly, valve seats and cylinder head gasket (most likely) are suspect.

You should be able to tell, with spark plugs out, and fuel system engaged while cranking the engine, whether cylinders are receiving fuel at time of crank. Disable the cold start injector if you can by pulling the harness connector from it. Of course, wholly disable the ignition system by pulling the wires from the coil before allowing fuel vapors to spread. Observe safety.

I'd start with electrics. The check for OBD fault codes. A wiggle of the crank position sensor (CPS) cable may not have much effect if faulty. Usually, the fault is in a failing cable insulation or a break in the conductors therein at the sensor. You can easily find CPS replacement for cheap or free from your local Volvo equipped salvage yard. Usually these, and other sensors, are replaced by the time a RWD Volvo end up at the junkyard before ending the life of the Volvo automobile. If indeed a failed CPS sensor or missing CPS signal induces a no-start condition.

Check fuses, wire harness connectors in the engine compartment.

Look at the distributor? Looks okay?

Relays in the under dash center console relay box need a wiggle?

You may need a multimeter to verify expected voltages at connectors and such.

How is the fuel rail pressure regulator? Leaking through the diaphragm into the air intake port (same as air intake manifold, yet a port on fuel injected engines).

Do you have starting fluid? You may want to have an assistant crank the engine while spraying starting fluid into the air intake before much else.

Questions?

cheers,

MacDuffed.
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Duffed.