I have a vectra x20di, year 2000 for about six months. Severe loss of power, engine light on, wouldnt rev over 3000. Have been reading about split pipes, sensors etc. I decided I had had enought and would take a day off and cure it. I removed EGR and connected it directly to the vaccuum pump. It opened immediately. (so eliminating EGR valve and pump) I then connected it to the outlet of the solenoid, revved to 4000 and valve opened and closed. I carried on connecting the valve to various pipes until it stopped working. I found 4 split pipes (ones that I had checked, but obviously not well enough. So just use the EGR valve as a vacuum tester. Car going like a bat out of hell now.