My 2000 yukon denali starys right up but surges and stumbles until it warms. Occasionally it doesn't want to take throttle from a stop, doesn't die, but its as if the thottle and peddle arent connected for a few second and then is fine. I cleaned the EGR valve and it is marginally better. Only code it threw was a P0404. Not sure if the EGR is indeed bad or where to head next. Thanks for any help.