I have a 2002 E150 with 4.2l V6. The problem is an apparent miss that shows up usually in overdrive while trying to maintain speed on a hill or gently accelerate from around 50 mph. If I turn off overdrive in these conditions the miss does not usually appear. I have changed plugs, air filter and oil and run some injector cleaner through with little improvement. The problem seems worse when the fuel gets below 1/3 tank. Any ideas or suggestions out there?

 

You might consider changing the fuel filter too.
If you still have the problem you might consider checking the fuel pump pressure and current draw under load. Most folks don't have the equipment to do all the testing we suggest and you might have to either rent it or have it done by a reputable shop.
A side note, some Ford engines don't like spark plugs that aren't Motorcraft brand. It's weird , I know , but it's true.

 

Thanks, I will change the fuel filter when we scratch up enough money to get one and look into your other suggestions. I appreciate your time and expertise.

Phill