I recently purchased a 1989 YJ with a 4.2L 6cyl. engine. It had the vacume booster for the brakes replaced and now every time the brakes are applied coming up to a stop the vehicle idles down and stalls. Also the windshield wipers run very slowly which I am guessing are being affected by the same vacume loss if vacume boosted. Sitting idling it runs find and going down the highway it runs ok. its just coming up to a stop when you apply the brakes. If you can keep the rpm's up its fine Any idea's?