Nissan Sentra 1988 - two door

My Nissan Sentra 1988, two door, mileage at 196,038 as of today has been running just fine 'til yesterday. I have had this car for about three weeks and know the previous two owners, who both maintained it very well. Must admit to not knowing much about what goes on under the hood. Anyway, I was driving home yesterday when the car started "juddering", by which I mean driving very lurchily, as if, perhaps, fuel wasn't "feeding through". I was doing about 70 km/hr and in 4th gear, so I tried slowing to 50 and downgeared to third, then up again, but the problem persisted. At first it would only do this occasionally, and then drive normally again, but the problem seemed to worsen. A friend and I checked out the fuel filter and that seems to be OK. The car also recently had an oil change and was inspected for insurance purposes and no problems were discovered or reported (although I don't know how thorough they are). Friend suggested it might be the. Hmmm. Forgot the name of the part. But it's about the size of a can of beans and has two hoses attached, one, apparently bringing fuel in, the other out?
Please help! Charlotte