1999 mecury cougar loses power sometimes while driving rpm goes from 2-4
so you saying the RPM gauge changes......not good. either the trans. is slipping or the trans mission kick down is engaging ..
I'm going to have to suspect a clogged EGR valve....because it is at the specific RPMs that the EGR wants to engage on de-cel....if buggered with carbon would be delayed or inappropriate engagement~ clean it with brake cleaner or replace it~
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