1992 Chevy S-10 intake leak

My 92 s10 4.3 vin z has a proublem, if you tap the gas it will rev then rev to about 2000 rpm then come down slowly it had a m.a.p sensor code a while back so i tightend the intake manifold its the same, i sprayed brake cleaner around the intake no rpm change except at the egr valuve so i replaced the gasket, could it be the intake manifold gasket? Thank you for your time