Loud vacuum-like sound during acceleration

Just finished replacing the transmission & rear Ujoints in my 94runner. Can someone explain the loud vacuum-like sound behind/under the dash when I accelerate & how to eliminate it? It's beginning to aggravate me :banghead: ! The pickup just isn't there anymore either, especially when driving up a hill. I drove up a long steep hill with the pedal down to the metal (ECT power on & O/D off) and it kept shifting gears. Along with that, there's a loud suppressed screaching sound under the dash (maybe tranny) when it shifts from I think 3rd to 4th gear, then disappears. Help anyone???

I want to upgrade for better performance. Any tips or suggestions for a 94 as far as power, brakes, suspension, etc.? I'm naive to this high performance stuff :uhoh: .

same thing happens to me. ever fix this?

Check that all your vacuum hoses are connected and no open vacuum ports.