Acceleration problems

I have a 94 Isuzu Rodeo that also sounds like a locomotive at times (that's in another post..heh). The problem I am putting in this thread is that when accelerating, the truck seems to spit and sputter, and accelerates even slower when you try to floor it for more power. It almost feels like it is congested somehow(if that makes any sense). Sitting in park, it accelerates fine, except it still is a tad rough. Could this be a timing issue? My fiance has heard about something like this being caused by oil leaking into the combustion chambers, but I don't notice any oil-burn smoke. Any ideas?

possible exhaust restrtiction Catalytic convertor
have someone check backpressure

Just had the exhaust checked today...Clean as a whistle (what a bad pun in reference to my locomotive sound post). I guess my next step is to check the timing. Anyone know the timing specs for the V-6 in a 94 model?

Found the solution to the problem today... Changed the plugs to Bosch Platinums. The old ones must have been the originals, because they looked like hell. LOL The gap on the old ones were so burned that they must have had .080' gap. It's a wonder this poor truck ran at all. New plugs and wires are in it now and it runs better than when it was bought used 1 year ago!