Volvo 1987 240 Wagon

For the past six months I have been trying to locate a really frustrating engine misfire problem on a Volvo 240 station wagon.
I am now at a point where I will not let this car beat me but I am competely lost as to what to do next so hopefully some kind person can give me a few suggestions.
The engine misses in open and closed loop across all cylinders. No fault light on the dash. The engine starts second time, I always have to turn the key enough to engage the starter then let go, I sit and wait for the fuel pump to pump the fuel to the engine and I can hear this happening. Once the pump stops pumping the car will start as soon as I turn the key for a second time.
I have new plugs, plug wires, distributor cap, rotor. I have a new PCV valve no vacuum leaks but vacum test shows 17 hg. I am near New York city so close to sea level. I have installed a new fuel regulator, swapped the mass air intake, swapped ignition timing unit in engine compartment and the ECU inside the passager foot compartment. I have installed a new wiring harness, clean thotle body, replaced intake manifold gasket. Compresion test show 140 which is low but within tolerance - or so I am told. I have checked and set timing. Oxygen sensor and temperature sensors are giving correct voltage signels. I did change the cat converter as it was rusted.
Any ideas would be great - many thanks