Problem: 57 Olds 371 with a remanufactured Rochester 4bbl that was just installed. We worked through firing order, distributor, points etc and now it starts very well. However, it stalls as soon as it is put in drive.

My "fix-that-is-not-a-fix" is that I put a tin air-baffle with slots cut into it on top of the front half of the carburetor and that makes it run decently at lower speeds.

That said, it does not upshift or downshift quite as it should, is prone to occasional stalling at low rpm, and once the engine is fully warmed up, seems to be getting very little fuel upon gas pressure. This last problem is actually the worst--you are going along okay and then it's almost as if the more you step on the gas, the worse it gets until you back off.

To me, this seems like at least partly a vacuum leak or a poorly adjusted carburetor. Also, I had to set the idle slightly high to keep it running at low rpm (I would say about 10% higher than it should be).

This car has a new electric fuel pump and, as I had indicated, a new Rochester.

Any notions as to what is bedeviling this otherwise solid engine?