I had a 92 Caprice 305 with an intermittant borked EGR valve which was causing oddball hesitation and spongy acceleration. The car has 300k+ miles on it so it did take some time to diagnose it even though the car is in tip top shape.
I disconnected the EGR valve and plugged the vacuum hose and now I notice the car has a LOT MORE POWER along with much quicker throttle response. This car has run like this in the last 100k miles and I just figured the motor was getting tired.
So what gives?
I'm getting no knock, no ping and the temp gauge shows nothing odd and with the exception of the Check Engine light with EGR codes, the car is running incredible.
BTW I remove and clean the egr and passages of carbon each year before inspection so nothing in there is plugged. The valve is bad I know for sure.
I'm suspect I will have to spring for a new one when inspection time comes around because the nox will more than likely be high, but WOW what a difference in performance.