1988 Oldsmobile Cutlass code 34

Engine Performance problem
1988 Oldsmobile Cutlass 6 cyl Front Wheel Drive Automatic a lot miles

oldsmobile cutlass ciera 1988 3.8 engine: I have recently repair the engine but I have problems with rich fuel mixture, I scan the engine and found the code 34, that sais its the map sensor, so I check the time and found that the ecu is retarding it and the fuel mixture is enriched, that told me that there are vaccum leaks so I check them and didnt find anything, the car doesnt have catalyc converter and the o2 sensor is working fine, what else could it be