92 Suburban only runs when engine revved

I have a 1992 Chevy Suburban, K1500, 5.7L, 160K miles which recently had it's gas line freeze in bitter cold weather. I towed it home and let it warm in the garage a few days. It is much warmer now. However, now, I can only get it to start using starter fluid sprayed into the carburator (it has TBI). Once it starts you must keep the engine revved or else it dies and won't start again - unless, of course, you spray in the starter fluid. I replaced the fuel filter and it still behaves the same way. All the ignition components are relatively new (1 year or less) - distributor cap, rotor, wires, plugs. I checked distributor cap for condensation, but there didn't appear to be any. I suspect the fuel pump, but it is puzzling, because the engine runs well at higher RPMs, which would require greater fuel throughput from the fuel pump.