Thanks Steve. When I tested it, I used aligator clips and the connection for some reason wasn't good and I assumed it was bad. I lubricated the valve with WD-40 after I cleaned it with electric parts cleaner and oiled all the throttle linkages. The valve rotated as you described. The car idles great as before the cylinderhead rebuild and has plenty of power. I believe a combination of a dirty valve and dried/unlubricated linkages (the problem happened after I degreesed washed the engine). Thanks again.
1993 190E 2.6
Advanced Diesel Systems Test and Research Engineer