Window Air Conditioner Leak

I have a window air conditioner unit that runs fine for a while and then it starts to leak on the bottom into the room -- so it looks like it is not draining properly.  
I raised it up with a 2x4,   so that the AC Unit is angled toward the outside of the window, which has helped a little bit.   When it starts to run rough or spit water out of the fan area, I shut it off for quite a while but it is still having an issue.    I read that you can drill holes in the bottom of the unit (outside area) to help drain it,  but some posts indicate not to do this.    The other option is to just run it in fan only mode to dry out the drip pan.   I wanted to see if there are any other ideas/options.    Please note, I would replace the unit but they do not make this style anymore - its a low profile for fitting in windows that only raise up 8-9 inches high.  I do not want to purchase a portable AC Unit as I have read too many negative reviews that they do not cool sufficiently enough.   Thanks for any info.