1998 Oldsmobile Silhouette Starts then stalls

This weekend I installed an inline block heater and battery heater on my Silhouette (in preparation for Alaska winter). The inline heater I just spliced into the lower radiator hose and then I removed the battery to install the heater pad under it. The battery may have been disconnected an hour or so. Upon reinstalling the battery, I went to start the car and in the key first position, my idiot lights all blink on and off and when I start the car, it starts but then immediately stalls. According to my manual, this could be a vacuum problem or ignition problem. But since I didn't touch any of those items, I can't see how it could be them. Also, I just installed a new starter a month ago, and the battery is a 4 month old Interstate. There is some funny clicking in the relays at the engine fuse box, don't know if maybe one of those got shorted or something? Do you have any ideas? Prior to yesterday's work, the van was running great, even with all of its's miles. The only thing I know I did in the install is to get some coolant on the engine near the lower pulley, when I cut the hose. Other than that, the work I did was pretty straightforward and non-invasive.