98 Deville runs rough at cold start

My 98 Deville has recently started running fairly rough upon a cold start-up, it smooths out after it's warm, I thought it was an EGR valve, since it would also give a bucking or buffeting notion at around 45 mph. I have 125,000 miles, recently replaced plugs, wires, gas filter, fuel pressure regulator and EGR valve. The bucking has gone away but the rough idle at cold start has not. Possibly a bad injector or carbon build up in the intake? I don't know, it hasn't had any major repair work throughout its life. I don't know how to diagnose bad injectors without going to the shop, dread!

Any ideas? Thanks

It is normal for most cars to have a rough start in cold weather. This is because the oil is thick and needs to warm up and move through the engine. If you live in a cold climate, I would recomend using a lighter oil such as 5w-30 or 0w-30 if cold starts are frequent. I let my car idle on cold morning for about ten minutes before I drive. Hope I helped.

I beg to differ. My last few vehicles start up and idle fine, even in cold weather. I believe this is because I keep my vehicles well maintained; which it sounds like you are thrying to do. I highly doubt it's injectors. It's those little things I'd be looking at like the EGR valave, PCV valve, fuel filter, etc. I have two other questions for you to consider though. First what grade of fuel do you use? These Cadillacs are designed to run on premium (93 octane) which burns cleaner. Second and more important question; what type of plugs did you put in the Caddy? From experience, trust me, GM vehicles only like AC Delco plugs. You might be able to use aftermarket fuel filters, air filters or whatever, but ONLY use AC Delco platinum tip plugs in your motor. I don't know why this is but I've seen it an numerous GM vehicles.

Did you cross a couple of plug wires,,that would make it run rough