I would think it would only effect the cruise because it could cause a vacuum leak? I know on older vehicles the cruise works via vacuum. I just don't need a vacuum leak and I was running knock free on a 3.5 then started to get KR slowly over the past few weeks. Ported the blower and it just kept steadily creeping higher so I replaced the beat up upper mounts and swapped the fuel filter which was dumping blackened fuel so hopefully its gone.