'02 5.3ltr problems under load misfiring

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Crazywelder72

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i have a 2002 Tahoe 5.3 and let me start by saying that even tho i am mechanically inclined, i am not a mechanic.

The problem is intermittent, the truck will start and run normally and even revving the engine it dosnt start the problem. while driving and accelerating all of the sudden you have a tremendous loss of power and bogging, sputtering exhaust sound changes and hard to make 30mph holding the foot to the floor. the Service Engine Soon lamp starts flashing but not storing any codes. Sometimes it will finally stayed lit and held a few codes:
misc cyl misfire PO300
Bank 1 too lean PO171
Cat sys to low Bank 1 PO420
Cat sys to low Bank 2 PO430
O2 Sensor vtg low bank 1 sens 1 PO 131
this vehicle has always had excessive oil consumption but has never smoked (consumes a quart every 2k miles) but always had a issues with a 02 sensor sens 2 (i just forget which bank)


i changed the fuel filter and all 8 sparkplugs today but the problem remains.
(the plugs were interesting and i will post pics later but all on drivers side were carbon covered and passengers side were lean looking. all the electrodes had similar wear.

after another test ride i got it to run like like crap again and while it was running like crap i got a vac gauge on it to the port on the intake. the needle was steady at -16. I sprayed all around the vac lines and everywhere with starting fluid and had NO change in the needle or idle. When i revved the motor the vac would climb to 0 and back to -16 when i let off.

i am thinking about the fuel pressure regulator first thing tomorrow but NAPA has a few listed for my truck 50psi, 56.56psi, and 62psi. and the prices range from $50 up to $115.

How do i know which is the correct one????

After that i am STUMPED and need help!!!!
 
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Crazywelder72

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Sorry, I posted this in the wrong section. Administrator can close this one as I reposted it in the proper year section.
 
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