damien4uuk said:
If its this limp mode thing how do you stop it from happening?
limp home mode retards the ignition and you loose loads of power, it can go into limp home mode cause of dodgy fuel, cause the timing is out, or cause the knock sensor is faulty, and a couple of other things. when you turn the ignition off it lets the ecu go back into normal mode.
do a search for the following things
"fault code check" - find out how to do it and test your car, it takes 5 mins and 0 mechanical knowledge, but is better explained in some of the many problem solving posts
check it for knock sensor, code 3,4 then.
reset all codes go out and give it a blat.. come back and check again.
oh and make sure your running on optimax
best of luck.