95 gmc g2500 vandura

I have a 95 GMC g2500 Vandura I have been working on. When it was brought to me it did not have any power and would bog down when accel. I gutted out the converter that was clogged and it still bogged down. come to find out the van had sat for nine years and the gas tank was slam full of rust so the fuel pump, filter, and gas tank was replaced along with a rebuild of the throttle body. The van ran amazing after that but now is running extremely rich and has a code 34 (map sensor) and I cannot figure out what is causing this to run so rich please help… it has a 5.7