Hello all. i have a vectra 1.9cdti 150. I noticed a shudder in 1st gear at 4,000rpm. Now i cant get past 4,000rmp in any gear. The car is still running fine and i have no EML showing. Accelerates well upto 4,000rmp but wont pass. I had EGR valve replaced 4 months ago, could this have caused a problem. Can anyone advise....