Nat67
Rockgoblin
That there be a power commander 3 , I had one of them play up giving the symptoms you describe . It plugs into the main loom under the tank . The 2 large grey stock plugs are pulled apart and each plug connects to the power commander plugs . Disconnect the power commander and reconnect the stock plugs together then see how she runs . If the problem remains then it is unlikely to be the pc3 . Oh and welcome from one of the Brits !