1990 Mercedes Benz SL300 Battery discharge

I have a 1990 SL300 that the battery goes dead after a day. The car is usually stored in a heated area but now its in an unheated garage. This problem just seemed to start when we had our fisrt real freezeing temps.
I hooked a Snap-On graphic meter between the battery. Bypassed the trunk light and the meter read a 0.110 amp draw. I have done the following tasks without finding the problem or reducing the draw. Removed fuses and fuseable links in 3 fuse boxes one at a time. Disconnected the alternator. Removed the aftermarket radio. Car is completly original and well maintained. The exception is that an aftermarket radio was installed a couple of years ago.
Could there be a stuck relay?
Is there a fuse or fuseable link not located in the 3 boxes?
Backfeed from one circuuit to another?
Is there a timer icircuit that is not shuting down?
Any ideas would be helpful.
Thanks