The project 245 continues to give me fits. 1989 with 230K. I bought it the first part of June, did a bunch of rehab work so it would pass state inspection, enjoyed it for two weeks, blew the head gasket, then replaced a ton of stuff while I had the engine apart for the head work.

Car behaved fine for a few weeks once it was all back together. Then it developed a noticeable hesitation when coming off idle. Idle has gone from being very slightly rough to quite rough (think: "gosh, is there an orgy happening inside that car?"), with noticeable episodes of missing. It has never stalled. Otherwise, appears to perform fine. Throttle is clean, switch clicks as soon as I start to move the linkage. injector seals, intake gasket, throttle gasket are all new. Vac lines are all new. New OEM cap, rotor, plugs, wires, CPS, coolant temp sensor

Vacuum gauge performs like scenario 3:
http://www.secondchancegarage.com/public/186.cfm
except during the intermittent misfire and severe rough idle episodes, when the vac. drops to about 5 or so and fluctuates wildly. Note that scenario three is considered normal for a high-performance engine, it is presumably NOT normal for an unmodified B230F. Any thoughts on that? The machine shop that refurbed the head adjusted the valves, too--I have never messed with or checked them. Machinist does lots of work for the regional volvo shops, so he should know what he's doing--I don't.

I have swapped out AMM with freshly cleaned ones from the junkyard. While it is possible I have 4 AMM's that are all bad, I think this is unlikely. Clips in the connector are clean and tight. Flex hose from AMM to throttle is new, all connections tight. Airbox flapper permanently set to fresh air.

ECU was replaced with a -951 when the car was only 3 years old.

When I unplug the IAC, the idle shoots up to about 1500 rpm. It is normally around 1000, if the tach is to be believed. IAC was cleaned shortly after I got the car.

Because of the head gasket, I was concerned I may have ruined the O2 sensor (which I'd replaced along with the cat only a month before). But the sensor appears to perform as expected during the usual voltmeter test.

As this is a 1989, there is no schrader valve on the fuel rail or under the car near the filter/pump, so checking fuel pressure would be a pain. Both pumps have been replaced with OE pumps, new sock, new main filter, new FPR. Flex hose from pre-pump to sender assy. was in perfect condition, no need to replace. (Thanks for the replacement float ball, Art!) The pumps were apparently original--the main pump was liberally slathered with Volvo undercoating, so I don't feel bad about going through all that work for what turned out to be "preventive maintenance".

Any thoughts? I miss driving this car!

thanks,
John