Whenever I set my cruise control below about 70mph it seems to surge when maintaining speed, kind of like trying to maintain speed without cruise control. What do yall think? Vacuum leak?

 

Mine never did it until I got a reflash done about a year ago. Ever since then it does as you describe. It keeps the speed but not smoothly. Mine seems to go away above 65 mph. Of course the dealer says it's normal!!!

 

mine will have the problem like this in the hills. It ONLY does it when the BD is on performance. When i set the cruise to say...78 and i go up a hill it will input a little throttle to keep speed, then when it hits the set speed it will let off completely and jolt you forward. it especially sucks when going up a hill, then back down that hill. It will let off and jolt you forward, then press the throttle to maintain speed going downhill. at the bottom of the hill it will get on the throttle again, hit 79 and jolt you forward. it takes about 3 miles to get in tune.

seems to also only happen above 70mph as well.

 

If you have not solved the 70 mph buzz/drone problem on your 03 then the buzz seems to vibrate the APPS when no pressure is on the accelerator pedal
cable. I posted on the cruise surge @ 8 months ago, then when I solved
the engine buzz problem my cruise no longer surges. Search for my post
on the buzz from about 3 months ago. Simple to fix, big results.

HOUTEX............