I have heard that by pumping the accelarator with ignition off can sometimes reset engine....is this true or not? Any suggestions would be much appreciated

It's normal - the ECU goes into relearn mode. It cures itself as it figures out what it's doing.

is it good for car in general to relearn

It's not a bad thing. Leave it disconnected for an hour or so to fully drain the power. Hook it back up, turn the key on (but don't start the engine), and wait for the high-pitched humming to stop (that's the TPS adjusting itself on pre-dbw cars, and the throttle body aligning itself on dbw cars. When it stops, crank it up and hit the road.

Thanks for the info, i will try that now and let you know how i get on. Much appreciated.

I left the battery disconnected overnight, reconnected it, turned the ignition on and left it a little while. Once i started it it began to rev at about 11/2 again. I turned the engine off, put my foot on the accelerator for about a minute or so started the engine and away it went. All fixed.