Ok here is my report.
It turned out to be the EGR system. The tube and valve were completely plugged. After building a special roto-rooter tool. I was able to clear the tube out. The valve was easy to fix. I took it back for the re-test and it passed with lots of room to spare. I was really pleased. The idea of buying a cat was not my idea of having fun.
I have to admit that the Shiner Bock was consumed during a small celebration, but I have another case on ice waiting for you Jim.
Thanks for all the good ideas. This forum is great.
I got too many cars!! Insurance eats me alive. Dave
78 Corvette Stingray - 3k
82 242 Turbo Volvo - Manual - 270k
86 300e 5 speed manual - 210k
87 420sel - 240k
89 560sl - 78k
91 420sel - 205k
91 560sel - 85k
94 GMC Suburban - 90k
97 Harley Davidson Heritage Softail - 25k
00 GMC Silverado 1 ton 30k