I had the day off from work so I went to the mat with the 240. It had a miss coming off idle which got substantially worse under load. It was worse when the car was warm, almost normal when cold. The Bosch copper-core plugs were only a few months old and there was plenty of spark. Newish wires.

In the last few weeks, I have:

Replaced the dist cap and rotor
Replaced the FPR.
Replaced the main fuel pump and filter.
Replaced the Fuel pump relay.
Swapped in another MAF, then swapped back in my reman'd unit from FCPGroton when the swap changed nothing.
Swapped in a spare Throttle position switch.
Today, replaced the block temperature sensor, intake manifold gasket, ignition control unit and 02 sensor.
Checked everything for vacuum leaks.
Re-routed wires away from the harness serving the crank position sensor.

No dice.

So I finally broke down and took it to a mechanic who does old Volvos. He did a smoke test on the intake system, no leaks, checked the timing, dead on, checked the ignition voltage, everything good. Finally he asks: What kind of plugs do you have in there, and how old are they? When I told him, he said: Oh, you gotta get those Bosch's out of there, they're nothing but trouble, they don't like the methanol gas. Where do you buy gas, do they have methanol? I said yes.

So he told me to put NGK Copper plugs in there and gave me a list of gas stations that sell un-oxygenated (non-methanol) fuel.

I swapped in the NGK's. The problem is FIXED. The car runs like it's new (of course, it's about 20% new NOW). NGK BPR6ES. 9 bucks a set.

I'll never use Bosch plugs again.

Thaddeus