Halp03

My 2003 Pathy is pathetic at the moment... Usually the best starting vehicle around. Starts and sometimes t/o for a full 30secs before starting, anything above slow acceleration, (Cuts out) and if it has run long enough to warm up a bit becomes impossible to start. Changed the Fuel Pump.. . Have run it up to 4000 + revs comfortably, but in reducing rpm can climb back up to 4000 + but if falls to 2000 rpm stops and won't start.