5 Computer codes, rough running, not MAF or fuel filter.

[PropertyCO]

98 Mazda b4000 (Ford Ranger, 4.0)

Been running rough, misfires and what not for a few days, i have no other option but to continue driving as i work an hour away from where i live and this is my only mode of transportation.

Started after the hour drive home, ran fine on the free way, i got off, started sputtering and misfiring.

Changed fuel filter, plugs and cables are only ~3 months old, cleaned MAF and even tried a new one, no avail

I'm thinking DPFE?

Codes are:
P0174
Low fuel pressure
Large Vacuum Leak
Dirty/Defect MAF
Engine Mechanical Condition

P0171
Air/Fuel ratio bank 1
Low Fuel Pressure
Large Vaccum Leak
Dirty/Defect MAF
Engine Mechanical Condition

P0303
Cylinder 3 Misfire Condition Dected, Probably cause:
Lean air/fuel ratio
Weak ignition system
Engine Mechanical Condition
Vacuum leak affecting one cylinder
P1132
Heated oxygen sensor - Bank 1 sensor 1 rich condition correcting for over lean condition, probable cause:
leaking injector, regulator or excessive fuel pressure
Engine vacuum leak or open EGR valve at idle
Engine mechanical condition
Failed h02s11 (Bank 1 sensor 1) or MAF sensor

P1151
Lack of 02 switches bank 2 sensor 1
ECN could not adjust fuel trim because of a lean or rich condition, probable cause:
fuel pressure high or low
maf sensor dirty/defect
vacuum leak on engine
leaking fuel injector or fuel pressure regulator

Coil pack measures with in specs
I know that i'm missing an 02 sensor too, but it has ran fine with out it since i bought the truck.

Another thing, when i was taking the coil pack out for testing, noticed there was the forward most line disconnected from the DPFE, from what i hear this can be cause from too much back pressure, maybe a bad cat?

I've also sprayed down the vacuum lines, don't believe they're bad.

edit:
Runs fine when reving, when i stomp on it it'll drive fine, occasional misfire at high way speeds, if i'm at 2k rpm in third gear it'll drive fine, but when i give it a little gas it'll sputter, idles fine when cold, stalls often when idling and warm

[Jswifto]

Your lower intake gasket is leaking badly the 0171 and 0174 are lean codes.

[PropertyCO]

I could believe that.

What would you estimate the time of this replacement job to be (in a perfect world) like 3-4 hours?

And what gaskets would I have to replace on the way to getting to the lower intake?

[Jswifto]

About that time frame you just need to get the intake gasket set it will have all the gaskets including the valve covers.

[PropertyCO]

i read a few places that lower is only needed with SOHC, i don't believe mine to be SOHC.

Do you think just the upper would be good?

[Jswifto]

When you pull the upper off the bolts for the lower will be loose like hand tight. You need to go ahead and replace the lower gaskets.

[PropertyCO]

alright, only reason i'm asking is cause i'm doing it out side in 4f weather haha.

[De-ranged]

I know we're talking apples and oranges here; but I had a similar issue on my '02 Lightning. Chased it for days before changing the front o2 sensors and that fixed it. Just a thought for you.