1996 Ford Escort hiccuping loss of power misfiring

Hi my name is gaz my car fires up and drives beautiful but after i have been on a long journey, parked up, then go back to the car a few hours later, on my journey home the car hiccups misfires and eventually stalls. She will fire up again but soon does exactly the same a few minutes after, if i rev her she constantly backfires and doesnt go anywhere until eventually she drives normal again.
She has had new spark plugs, ht leads and a coil pack i have also cleaned the idle sensor and the throttle body. Can someone please help?