Why is my Vauxhall Frontera stalling ?

for the first time tonight my car stalled for no reason. 1st occasion at an uphill juction, then on a downhill juction then finally when idle. starts fine but stops with no warning. Also just after re-starting the engine revs increase on their own ( and oil level display increases but this is only when car pointing uphill. )

any advice much appreciated

Paul Brady
November 2004