1986 Honda Civic map sensor problem

Engine Performance problem
1986 Honda Civic 4 cyl Two Wheel Drive Manual

so I have a honda civic 86 si. The problem is the ecu shoots me error code 0401 disconnect map sensor piping. So I replaced the map sensor and it worked for a day and then it was back to acting the way it was. It was hesitant and the car would jump up and down. I get bad gas mileage and I was running on the rich side. So I got it timed replaced the ecu and spark plugs. But none of that worked. So back to square one. Im thinking its a vacuum leak, pcv valve, or egr. So what could it be?