Well guys, I know this was a long time coming, but I figured I would post an update. Thanks for all the help! I went ahead and upgraded to the newer afterglow relay and chose to replace the stock temperature sender with the updated one. It wasn't as hard as I thought...just had to be creative. I removed the injector lines for cylinders 4-6, and then used a crowfoot line-wrench socket to loosen the temp sender behind the injection pump. Popped the new one in and used new connectors for the new wire to make it look as stock as possible. I also changed my block heater because the old one had burned out.

The results were dramatic. Not only is the relay functioning properly again, but I have never experienced such smooth starts since I have owned the car (almost 2 years now). Without the block heater plugged in, it was 20 degrees out, I let the light cycle and waited about 5 seconds after the light shut off...she fired right up. No missing, excessive smoke, or anything. Makes me wonder how long the old relay had not been up to par!

Anyhow, thanks again...love this forum!

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97 S500 (90,000 miles) - wife's car
87 300D (298,000 miles and a replacement #14 head)
94 Suburban K2500 - need something to haul firewood
83 300SD (343,000 miles) (sold)