I have a 98 GMC sierra SLE ext cab with a 6.5 turbo with 218,ooo clicks on it. Starting a few weeks ago I was having problems starting in the morning even though plugged in ( I live in northern Ontario Canada).Three glow plugs were gone so replaced all 8..still had same problem, peplaced pick up pump, still having same problem, replaced oil pressure sensor, still same problem, injector pump was replaced a few years ago when GM had recall on them. I live in a small town and there are no diesel shops here so am just going to local garage. I would greatly appreciate any help that I can get from anybody here as what the problem might be. Also have noticed a reduction in power and fuel milage in the last little while. Checked turbo out and vacume and waste gate are good. I have owned this truck since I bought it new in 98 and have never had any serious problems until now. If anyone is going to reply with ideas please put it in full explanation as I do not know what , for example, PDM means so please be specific in explanations. Thank you all..hope to hear replies soon as this is the only vehicle I own and I depend on it....thanks again very frustrated 98 GMC