Allison not upshifting during hard acceleration

[pushpole]

If I accelerate normally the transmission shifts fine. However, if I accelerate hard (as in pulling out to pass) the transmission downshifts and holds the lower gear. I have to lift the (gas?) pedal to get the next gear. Thanx

[Kennedy]

Quite possibly due for a fuel filter change. How thorough has your maintenance been?

[mikej39565]

Quite possibly due for a fuel filter change. How thorough has your maintenance been?

Yeah, I just had my dad's 2500HD in for same problem. They said it was a dirty fuel filter. Problem gone.

[pushpole]

I changed the filter about 5,000 miles ago. Based on John's observation (his opinion carries serious weight) I changed it 30 minutes ago. I took it for a test drive and there is no problem. I did notice quick a bit of debris on and in the water sensor. I don't recall seeing very much dirt there in previous changes. Maybe I recently got a dirty fill up. Thanx again to John. BTW my renewal dues are in the mail!