1987 Mercury Sable Fuel pump

I have an 87 Mercury Sable GS wagon 3.0 V6 converted to manual trans. It idles erratically and when revved to 2300 rpm it misfires and the exhaust smells like its running lean. When I drive it between 21000-3000 rpm range the engine cuts out. If I open it up all the way, the engine continues to run, but it has a bit less power than it should. The cylnder compression is where it should be, I put on new head gaskets 12,000 miles, new electronic ignition module, cap, rotor, plugs, wires, tested the coil and replaced fuel filter. I think the fuel pump may be failing. I have not yet checked fuel pressure or retrieved any trouble codes from the computer.