Can anyone tell me why my 98 Deville, 4.6L Northstar runs rough on cold start, it does this for a couple minutes until it gets warmed up then evens out and idles okay. I have 125,000 miles, recently changed, plugs, wires, EGR valve, fuel and air filters. There are no engine lights on. It almost seems like a plug or plugwire misfire and runs pretty rough, until it warms up. This just started happening, hope someone has a suggestion, thanks.

Look inside the vacuum hose at the FP regulator for signs of raw fuel., they are known to leak and this is one of the symptoms.

Maxwedge:

Thanks for the tip, I checked the vacuum hose to the fuel pressure regulator, no raw fuel, but whatever it did it seemed to fix the problem, the regulator was replaced about 2 years ago. Thanks so much, I think that fixed the issue!