1994 Caravan w/20K engine losing power for no reason(BAD SENSORS?)

[michaelfriedrich_2]

I just had my 160000 mile 3.0 V6 motor replaced with a 25000 mile motor from a 1996 Caravan. I know that all of the sensors, fuel injectors , and intake are all from my old motor (all I got was a new engine block and heads). A week after I put it in, I had to replace the fuel sending unit and the coil pack (it burnt up). I still occasionally lose power for no reason, like a lack of fuel...it falls on its face for just a few seconds. Doesn't matter if you're idling or going 55 mph down the road. It will do this when you first start it up if you don't let it warm up. I DON'T GET IT. This van would burn the tires off when I got it with 75000 miles on it. Is the answer in replacing a bad sensor or sensors?