egr valve on vectra 1.8 ls 2001 petrol?

please can somebody help me !!! i have a 2001 vectra 1.8 ls petrol which is misfiring we have changed all the spark plugs and filters and coil rail. we think its the EGR valve that is casuing the problem but we are having problems locating it. my brother owns a y plate 1.8 ls and the egr valve is located to the right of the engine but mine is not .