Why does my 2002 cadiallac deville sound rough when in idle and has a pulling or surging when driving and when at stop lights or stopped traffic/

SOURCE: 2001 caddilac Deville intermittant stalling.

sounds like an IAC motor. that stands for idle air control motor. it adjusts throttle to keep at steady speed. could possibly be throttle positioning sensor though. pay attention to see if it does it worse while mashing breaks because if EGR is stopped up it can cause symptoms similar too.

SOURCE: Idle surge 1994 cadillac seville

I have the same problem i found out that it is my cruis control has a leak in the hose and if you just disconect it you will no longer have cruis control but it should stop the problem

SOURCE: 2002 deville, 80K mi., Winning sound at start-up

It could be several things, most likely the idler pulley that keeps the serpentine belt tight. But could also be, power steering pump, altenator. ac compressor or water pump. The best way to find out is to remove the belt from the car by releasing the idler pulley tension. Then one by one check each component by feeling for slack in them and spinning them by hand to see if you feel
roughness. Good luck and dont forget to rate.

SOURCE: 94 deville w/4.9 engine,surges @ idle & will

check gaspeddel cabels on throttel body see if they are hung up pull on both outer cabels ehile running car

SOURCE: 2003 deville I have rough idling, surging and then

P410 code secondary air injection malfunction
It could be internal head cylinder problem
I would have it checked out