I have had a similar experience in my '72 Newport. One day, I slammed on the brakes. For a couple of days after, I heard a vacuum like whistle somewhere. Soon after, my car started running very poorly, accelerating like it had a severe vacuum leak. Feathering the accelerator was needed to get the motor to rev. Once at speed, the car ran smooth, tho I could tell a vacuum problem existed. I found that when the brake vacuum hose to the brake booster was taken off and plugged, the car ran fine. I bought a new brake booster but have yet to put it on. After I bought the new booster, it came to mind that it may just be the seal around the one way valve button on the booster that failed, this part fits loose enough to lose vacuum. I'm in the process of deducing the problem. Yet another potential area of failure for your '66. Hope this helps. Eric Portland, OR From: "Brian Shea" <bshea@xxxxxxxxxxxxx> Subject: RE: IML: 66 crown Date: Mon, 21 Jun 2004 09:54:05 -0500 Reply-To: mailing-list@xxxxxxxxxxxxxxxx as soon as it happened I pulled the air cleaner and the choke was wide open but i noticed a steam (smoke like cloud coming out of the primaries). Could that be the floats being stuck?It runs great as long as it is above idle speed.