Master of the Dark Art of Diagnostics
2003 DHS - two-2002 DHS, 2003 SLS, 1995 Sedan DeVille, 1989 Coupe DeVille
==========================Dear Friends, I had a similar problem with my 1988 Deville, 4.6 Liter. My mechanics finally figured out that there was a gap in the gasket at the injector housing. Does that make sense? This was several years ago. Air was leaking in and messing up the fuel air mix. The repair was cheap View attachment 583012 as I recall, and the car has run like a champ since then. Oh, I just got the horizontal surfaces painted and the rest of the body polished. Man, does it look good! I wish mom were around to see it, as Big Red was her car. The silver 2008 in the background is my daily driver. Ed
Dear Friends, I had a similar problem with my 1988 Deville, 4.6 Liter.
your car did NOT have a 4.6 Liter motor -
1988 was the first year for the new 4.5 motor - a VAST improvement over the infamous HT4100 -
the first Deville with the 4.6 Northstar was the Concours model in 1994 -