I just got done replacing valve cover gaskets on my 98 4.6 and I was heading to work went up a hill and it started to misfire I got to work and checked my connections thinking I plugged something up wrong but it seamed ok I plugged my obd2 scanner and it said my right bank was lean and I’m out of ideas so anything I could check 3 out of the 4 cylinders reported a misfired on that side


also Idles fine until hard accel or going up hills

 

Post all exact numeric P-codes.

 

there’s a lot more to this

 

So all I did was check my wiring one more time and my spark plug wire boots where not seated all the way that seemed to fix my problem but the lean bank still stumbles me I have no codes at the moment and is running fine the problem was my fault and should of checked that but never crossed my mind

 

I would throw a bottle of Techron in and some gas from a reputable station and see what that does.

 

"Top Tier" gas:

https://toptiergas.com/licensed-brands/

 

Misfires on 3 out of 4 suggest fuel injector connectors are not pushed in and locked, or the plug boots are not seated on the plug top ends or plug Wires at the coils are not seated if there was no issue before the work was done.
Good luck.