[djmtsu]

If the grommets are not seating well enough, you get a vacuum leak.

The oil pressure sending unit might have taken a hit when you put the engine in. Mine pegged to the top when I put my motor in, then the actual gauge broke. So now I have an Autometer replacement. Check the resistor thingy that is down there where the bell housing and engine connect (below oil sending unit). That can cause weird issues.



Is the motor a rebuild?