Just got my 90 and it drives fine round town BUT on the motorway i have real problems. if i try and go up any sort of hill then it kangaroos all over the place, generally after you have been driving steadily for a few minutes. i drove 300 miles like this and it wasn't much fun!

prime suspect is the float in the carburettor but i have been told it might be something to do with the fuel tank (broken/damaged pipe etc.)
is this possible even though the symptoms are the same on a full tank??

another possibility is the fuel pump but i'm not sure about this....

can anyone help before i set the garage on it??

Could be crap blocking the fuel pipe in the tank.

What colour is it, red ones don't go up hills very well.

haha. it's black. but used to be red strangely enough....

if it was crap in the tank wouldn't the symptons be more random?

Not necessarily depends on where the crap is how big the piece of crap thats doing the blocking is and how much suction is involved. If you drain your tank and there isn't any crap then you can rule crap out. How many times can any one legitimately get the word crap into one post?