After driving through some moderate flood water (estimating at it's highest, water got to level of bottom of belts on engine), got home, parked car in the garage, no problem. The next morning, turned car on, went to accelerate and the accelerator was stuck. Would still change gears (has automatic gearbox) and would move off in drive but no more revs other than idle. Tried to check throttle but coudln't get access to it as it is under a cover.

Anyone got any ideas?

Just an update to this. Undid plastic cover on top of throttle and throttle is stuck.

what year etc..?

1999 318i E46

Undid part of the inlet manifold so I could see the actual throttle plate and it was stuck so I gave it a tap and in works again. I'm not sure why it stuck in the first place but I think the fact that I drove it the night before through moderate flood water was just a coincidince as I don't see how water down low could have affected the throttle plate.