'91 Caravan has intermittent problem with low engine power

'91 Caravan, V6, all-wheel-drive, 70K miles.
Both my wife and son have experienced intermittent problems where the engine was running but produced very little power. My son was driving on the city streets and said that the car would just not go anywhere when the throttle was pressed. This lasted for a few minutes. My wife had driven about 4 miles on the freeway when the car started slowing down from 60 to 50 to 40 with the throttle pressed to the floor. On the way back from the her freeway trip, the car ran fine. Neither day was especially hot, the car was not overheating, etc. The car always starts easily and runs well otherwise. I have not experienced this problem yet.

I will try the engine codes to see if there is anything besides 12 - 55.

Any suggestions?
Does the Caravan have a fuel filter?
Should I do a fuel line pressure check?
Is the problem more likely fuel or ignition related?
Is the engine management system setting the ignition timing to extremely retarded, which would make the engine run very smoothly but with no power?
Enquiring minds want to know.

Thanks for your help.

A few things that I would check.
Do a compression check. If that is fine, check your timing.
Finally the most difficult thing to do, pull your fuel injectors and have them cleaned.
Never forget your oxygen sensor, that can produce a lot of headaches.
JOse.

The fuel filter on my 89 is underneath - loook under the side wall under the passerger door - I was glad I changed mine - it had regular fuel line hose instead of fuel injection hose & clamps - it was about to burst it was so cracked.