Well have my first problem that I cannot fix!
Back ground
2003 F-350 4x4 4 door got it used with 123000 installed bank's headers, y pipe, k&N cold air intake, five star tuner with 87 octane tune tow & economy tune. Now has 144000 miles and during a camping trip started throwing a lean in bank 1 code two weeks later through the same code as well as bank 2 lean then started missing at cold start up which seems to totally go away after the engine is warm .
So figured it was time for a spark plug change had all the spark plugs and the rubber protectors and springs change as well as the coil packs inspected for cracks none were found also replaced fuel filter so I assumed the problem was fixed Well it came back again today.
just looking for direction as to what to start looking At next.
Thanks.

 

Look for a vacuum leak.

 

Thanks I'm on it

 

Check fuel pressure.

 

Just in case the odds are against you ... last winter my 02 V10 developed a miss. My indy shop replaced the plugs and one cracked (overtightened) COP. Possible improved but a miss was still there. After 2 months of trying other things (several tanks of different fuel, new air filter, mass air flow sensor cleaned) this indy shop again replaced the plugs. Problem solved.

In fairness, I think the owners worker bee got lazy and didn't replace all ten. I say this because at original pick up the owner showed me 7 or so of the plugs. When I asked where the missing ones were he said they were trashed. Question: why would they save some and not all?

Eventually, upon once again returning, I mentioned this - and he remembered it. Of course he said no way, but ...

For the nay-sayers, the plugs weren't Motorcraft - they were Autolite (the actual manufacturer of Motorcraft plugs).

 

Ahhh yes but the nay-sayers will also say Autolite and MotorCraft are the same plugs, at least in this case.

 

It seems on start up "now that I have changed the plugs and the fuel filter" the miss or bogging down of the motor in park it seems that the AC pump cycling coincides with the miss or slowing of the motor! This still goes away when the motor warms up so I'm going to see it I can tell if the pump is going bad.