The once in 7 to 10 day stalling has finally come full term, and the car will no longer start, though it tries.

Last and only code pulled was P0171 (bank 2 too lean)
Over the past 3 months, I've replaced the following:
Fuel pump relay
Fuel Filter
All vacuum lines - also checked for leaks with propane and carb cleaner
Cleaned the MAF and TPS, AIC, and throttle body.

Up until today, it would stall about once /week and start back up.
Over the past week this became more frequent and took more time to restart.

I checked fuel pressure: At keyswitch position 2, the pump turns on briefly, pressurizing to about 15 psi, then shuts off. After the engine is started, the pressure builds up to about 40 psi and seems to stay there (using an old tire gauge to measure).

To see if power to the fuel pump is intermittent, I attached a voltmeter at the pump and monitored it from the drivers seat while driving around. During stalling, 12 volts was still at the pump.

Yesterday it would cut out occasionally while cruising and was sometimes slow to start. Car was garaged overnite, and today, it cranked, but idled rough (didn't want to rev)and brown/white smoke was coming out the exhaust, then died after about 30 secs. Now it won't start, though it tries.

I might have a new code set now, but won't have access to a reader before Mon.
If anyone has any suggestions, they sure would be appreciated.

Thanks,
Kcarl

Finally, replacing the MAF fixed it. Thanks for the input on this an other posts.

Kcarl

I'm not sure what's wrong with your car but I see one last place for a fault in your fuel pump diagnosis.

I'm not sure where you're monitoring the 12V at the pump, but it might still not be making it through the pump assembly to the electric motor inside. On my 1998 AWD (which has a pretty different fuel pump setup than FWD) the wires were actually broken inside the insulation right at the point where they went through the pump assembly. The pump motor ran fine when given 12V, but the power was intermittently not making it through from outside the assembly to inside the tank.

Just wanted to share my experience.
--
1998 V70 AWD->FWD Turbo 200k+

Thanks for the response. I clipped the meter leads on where the pump leads connect on top of the pump assembly, so what you're saying is possible.

This morning I tried to start it again, but it wouldn't go. I disconnected the MAF and it started and ran reasonably smooth (didn't drive it). To be sure, I reconnected the MAF and it wouldn't start again. I repeated this 3 times with the same results, so I'm assuming it's the MAF. Geeze I hope this is it.

I also tested the Cam position sensor (CPS), and it tested ok. I did this by ohming pin 1 to ground and got < 1 ohm. With the CPS sensor and shadow plate removed, I connected meter leads to pin 2 and ground, turned on the ignition and moved the show plate in and out of the hall sensor gap. I got a 0 and 12 VDC pulse. This tells me it's switching.

For who that might need one in the future, someone else posted this link to the hall switch http://www.newark.com/honeywell-s-c/2av54/hall-effect-magnetic-sensor/dp/96F1986. Here is the link discussing it on the Brickboard. http://www.brickboard.com/AWD/volvo/1311340/850/camshaft_sensor_repair_information.html