Truck runs like **** and idles rough and has no power running lean on one side and rich on the other

What is year--make--model? Fuel--spark--compression? Proper fuel pressure, is the fuel pump electric or mechanical?
If computer controlled, any applicable trouble codes? Can you tell if system is running rich or lean?
Usually with a rough idle, you check for a leak of some kind, fuel--egr--vacuum?

Check your fuel pressure and your fuel filter . Also check your pids.
which the most important one is your short term fuel trim while it's running ,it will be either rich or lean . I know it sounds silly but when the numbers are positive it's lean and when there negative it's running rich.

With the engine running try spraying a couple shots of carb spray into the throttle body. If the idle smooths out then your running lean. The next step is to check fuel pressure, vacuum leaks, and try unplugging the upstream oxygen sensor. It could be stuck rich which would make the computer drive fuel trims lean.

I’m happy to assist further over the phone at https://www.6ya.com/expert/jeremy_d728a59f986299fa

Maybe sensor is not for a bigger engine

For rough idle issues and problem troubleshooting,go through the help links provided below :-----van idles rough? http://howtobyme.blogspot.in/2012/01/2004-ford-freestar-van-idles-rough.html---------will not idle when cold? http://technoanswers.blogspot.in/2012/02/ford-explorer-40-will-not-idle-when.html
----------runs lean and idles rough? http://technoanswers.blogspot.in/2012/02/ford-runs-lean-and-idles-rough.html
-----------Engine stumbles coming off idle when warm? http://repairhelpcenter.blogspot.com/2012/01/engine-stumbles-coming-off-idle-when.html
------------Erratic idle on car? http://schematicsdiagram.blogspot.com/2011/12/erratic-idle-on-car.html
----------Low idle when cold out side? http://repairhelpcenter.blogspot.com/2011/12/low-idle-when-cold-out-side.html
---------Idle Air Control (IAC) Valve Replacing? http://schematicsdiagram.blogspot.com/2011/12/gmc-idle-air-control-iac-valve.html----------Engine quits at idle?

http://repairhelpcenter.blogspot.com/2011/10/engine-quits-at-idle.html

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Car overheats and Air blows hot at idle? http://howtobyme.blogspot.com/2011/11/car-overheats-and-air-blows-hot-at-idle.html
------While stop engine idles like cylinder missing? http://schematicsdiagram.blogspot.com/2012/01/while-stop-engine-idles-like-cylinder.html
---------This will help.Thanks.

On the lean area look for a vacuum leak anything there,like PCV hoses and pull the plug on the EGR is there a difference?Is the valve hot at idle? Now check the rich side pull the hose off the fuel pressure regulator is gas leaking out? MAF cant do this, IAC cant do this ,TPS, If everything checks out no vauum no EGR leak No fuel regulator leak you may have to find out if the 02 sensor is reading the correct bank .Bank one could be on bank two, and bank two can be one bank one,It could be mismatched

Before we both knock ourselves out with fuel injector testing. Hook up a Digital voltmeter (DVM) to upstream O2 sensor and lets see how she is burning. Remember positive lead of DVM to signal wire and negative lead to ground. Anything above 550 mV is rich anything below 350mV is lean. Be mindful that an exhaust leak the size of a pin hole in this region can cause a rough idle. A healthy reading should bounce between 550mV and 350 mV.
Next to test is O2 is working block off air in take making mixture rich and see what O2 says about it . Then pull off a vacuum hose (a lean condition) and see if DVM drops to 200to 300mV's.
Keep me posted.

Replace the fuel filter,have the fuel pressure check,it is most likely the fuel pump.

Flashing check engine light is missfire, fuel pump probably causing multiple tries to start.Having to build fuel preasure,vac leak on one side of intake probably causing rich/lean condition.Also check back preasure to cat ,Sound like you are moving down right track.Mas air flow would probably set lean code bank1 and lean code bank2

check timing and set idle to 650rpm