Ok, I've been getting a 2-3-2 code with higher than normal fuel consumption for a long time. I didn't check for a code until recently, and there is no CEL (not for this code). It's been getting worse, now about 16mpg mixed in town whereas I was seeing 21 back in August.


I wanted to make sure my FPR wasn't leaking out the vacuum hose (it wasn't), reattached the hose, and started the car.
When I pulled the vacuum hose off the FPR, it made no difference at all in the idle. I attached and removed it multiple times and it still made no difference.

My idle system works as intended, with the TPS working, the IAC valve working, and the idle is stable, but rough.
I started getting hesitation lately too. For a long time, I had some almost backfires when letting off the gas in park or drive and going slowly enough to hear it. I'm pretty sure it's running rich. It ran almost okay the other day when I accidentally disconnected one of the injectors. (This had been happening before that and it ran noticeably better when I reconnected it).

I checked the O2 sensor reading the other day and found it will run from .01 to ~.75V. It's maybe 2 years old and has seen some problems with mixtures (IE the breather boxhose being off and a blown intake hose for some months each). Sitting at idle, it's about .5-.55V steady. I thought the range was .01 to .9, but if it is really running rich, maybe it produces more like .7 max? is .9 max rich or max lean?

I think the O2 sensor is okay. The voltage seemed to change quickly enough, but I've only got a crappy centech digital meter, my analog meter bit the dust.
To my knowledge the FPR has never been replaced (it is the right part number), at least not since my parents bought the car in about 1998.

I'd appreciate some advice on which way to go. I would say I'll just wait until it dies and floods the crap out of the engine, but it would appear it might be already or it might take 6 months. I can't afford that, as I made less than 120 miles on more than half a tank. At the same tick mark on the gauge, I'd seen 140-160 miles in the past.

Thanks in advance,
Will
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1990 740 Turbo, on its way to stock specs, maybe beyond