I have a 1998 E-150 with a 5.4 engine. It hesitates under moderate acceleration especially around 40-50 mph. If I take it easy it will get up to speed but will still miss occasionally but not bad. Under heavy acceleration it will get up to speed fairly easily but you can tell it does not run as smooth as it should. I can hold it at 55-65 with little problem, but I have to have the overdrive off to keep the rpm's up. It also run great when it is cold. the problems start when the engine warms up. It also works better the colder it is outside. I live in Minnesota so it gets pretty cold but it runs much better in the winter than the summer. It has also been starting very hard in the winter if I do not have heater plugged in. Any one have any suggestions on what to check or where to start to look for the problem

 

Hi there,

I just thought I drop a line or two on this one.
I have the exact same problem for over a year now. Can't figure it out.
Took it to shops, all they want to do is replace every possible parts you can imagine.
I know I will offend some of the mechanichs here, but there are no mechanichs anymore. There just robots, following whatever the computer tells them.
Anyhow, I've been seing this problem on different sites, noone has an answer that would fix the problem.
I have a code reader, originally I've had some codes in the system, took care of all of them. No more codes for months now, yet the damn hesitation is still there just like you described it.
If it is any help to you, I'm thinking it has something to do with some sensors on the transmission or in it.
Maybe this will lead you to the right direction and you can post back and we can fix it, so the mechanichs will know too
Good luck my friend