4.6 liter engine with 170k. It doesn't feel like a coil issue (I've had them before at around 100k) and it isn't throwing any codes. It feels like the motor isn't getting enough fuel under a load. At half throttle and above, there is considerable weakness getting from 2000-4500 RPM . Idle and low throttle performance are fine. Changed the fuel filter recently with no change to it's performance. Any ideas?

My dads truck had a similar problem and it was just the spark plugs. They only had about 60,000 miles on them.

could be plugs or injectors dirty or egr problems. Need it hooked to computer and look at different PIDS to get a better idea. Also a oxygen sensor or MAF sensor can cause those problems also.

For starters, you can clean out the throttle body & MAF.

I had a similar problem early this year.
Between 55 & 65 MPH, my truck would be stuttering and sometimes hesitating but no codes.

After about 3 weeks of the issue, my truck finally threw a misfire code (Cylinder# 5).

After I changed all spark plugs and changed the coil on Cylinder# 5, my truck ran fine.

Probably coil/s, If you want motorcraft I'll sell them to you at a discount. UPS is no problem

its a ford be lucky it turns on.... It soounds like a plug issue

That's what I say every morning on my 2006 4x4. Even though it does have 165k
Miles on it. Hehe

No doubt I say the same thing every morning about my 97 and 06.
Not to be forgotten our service fleet of 5 E250's 1 F250 and 1 F150. The one chevy E2500 I worry about is it starts fine it's the pulling itself out of the parking lot is a different story. Otherwise we would just have to close our doors because we couldn't make any money.

CHECK ALL THE COIL BOOTS. USUALLY THEY BURN THROUGH AND ARC. MISFIRES CAN BE TRICKY ON A FORD.