95 Crown Vic Rough Idle coding p0171 and p0174 ( lean condition )

Hello Ladies and Gentlemen,
I have a 1995 Crown Vic LX with 175k miles on it.
I first noticed the intermittent problem as a single or double clunk when it
shifts from 2nd to 3rd and from 3rd to overdrive. I read the engine codes and they were P0171 and P0174 which are the lean condition for banks 1 and 2. Also spit out a P0307 (Cylinder 7 misfire) a few times.
I replaced the fuel filter as it had been in there quite a while. No change. Also had the tranny pan and torque converter dumped and new filter as fluid looked to be a pale pink with slight yellow cast. Bottom of tranny pan was very clean. Also added Lubegard Red. Not much improvement but thats ok cause I wanted to have it changed regardless.
Found nasty looking thick coolant in plug holes 1 and 3 from previously leaking thermostat housing. Cleaned out all plug holes (fair amount of dirt in all) and cleaned boots thoroughly. Still throwing the cylinder 7 misfire occasionally though. Gently cleaned MAF sensor with Windex spray and blew dry. Now the engine runs as smooth as silk most of the time and the tranny shifts so smoothly you can't tell except from egine rpm. However a couple of times a day it starts running rough again for a few minutes, looses about 1/3 power and throws both lean codes... and clunks between gears.
Got a Actron fuel pressure gauge and it was 31 psi engine running and the same with engine off and key on. Read it two days later and it was 40 psi key on and 31 engine running. Possible bad fuel pump? I have been trying to catch it in the rough idle mode and check pressure but have been unable to so far.
My questions would be how long do fuel pumps normally last and is 31 psi marginal for running pressure? Since the car is so old and has so many miles on it what sensors if any might i look at replacing? Four months ago it threw some egr codes for a few weeks but none since. Any other ideas?
Thank You, Bob
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Bob. Wells wrote:

31 psi at idle, I'd suspect fuel pressure regulator, or possibly a low voltage condition to the pump on the Run side. Read the codes after it's fully warmed up.
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