2000 Millenia S Millenium Ed. Engine Knocking

Hey I have a 2000 Millenia S Millenium Ed. I have a problem with engine knocking and shaking only after car sits for a long time and its cold outside. Once i rev the engine the problem is gone but then may randomly come back only when driving at low speed (under 30 or so) I took it to the dealer they havent found anything, the told me to use regular gas istead (dumb)..i did it became even worse..

Does anyone has same problem?? How did u fix it?

thank you!

Fuel has been a problem, according to Mazda. They are having problem w/Mill-S stumbling and carbon buildup. Contact Mazda for info on silent recall. They know they have problem but will correct for loyal customers- maybe

I have a 2001 Millenium and I had the same problem, but it turned out to be the knock sensor. Almost sounded like it was out of oil.

Maybe this helps.

those S models have been doing that for years man, let them sit at idle for a
long period of time and the supercharger will get noisey, the car will spark knock some, and on ocassion ive had misfire codes set from extended periods
of idling.... but i would check for vacuum leaks under the intake manifold. little plastic vacuum tees like to deteriorate and break