I have a sporadic issue where the van will suddenly seems to lose acceleration, almost like it shifted into neutral. It seems to happen a couple of times a week. I have noticed it traveling at 70 mph, at 35 mph, and (once) in 1st gear (low) moving around a parking lot. It happens when I have had the engine running for at least 10 minutes, usually having traveled at least three miles.

I have regained acceleration control by downshifting and repeatedly pumping the gas pedal, but it is scaring me. I have a 2006 Caravan SE, 4 cylinder, auto.
Any ideas? Other research suggests it might be fuel injector or fuel filter.