UPDATE #1: Did 4 coil packs on the driver side and it is, according to my brother, "95% better". Only issue is he said there was a lot of dirt on the motor and some fell into the cylinders on driver side. He said the spark plugs are blocking the dirt from entering but whoever changes the spark plugs next may get some dirt inside (is this a horrible thing???!!). He doesn't want to chance it and change the passenger side coil packs in case, by some wave of bad luck, it causes the issue to reoccur or a misfire, etc. So, problem solved.

OLD:

No check engine codes, no misfires, can rev up and sounds good, idles great, etc.

Problem: Lack of power when you hit gas, has hesitation, backfiring out of exhaust? Hard to explain I guess.

175K Miles.

Any advice on e-diagnosing it (!) as when I google "2006 Ford F150 no power" many threads pop up suggesting spark plugs and something related to the fuel pump?

Thanks!

 

UPDATE: See post 1. 4 coil packs on drivers side fixed issue.

I have an extra set of 8 coil packs that I was gonna put on to see how it ran....then maybe spark plugs...But maybe miraculously it is something silly like the Fuel Pump Driver Module???