1997 Other Saturn Models overheating

Engine Cooling problem
1997 Other Saturn Models 4 cyl Two Wheel Drive Automatic 101k miles

I noticed a slight coolant leak and took my car to my mechanic. He told me my radiator was cracked and suggested I use this product "liquid ice" to buy some time before replacing my radiator. I drove the car around that afternoon, but went out of town for 2 weeks and my car sat in my driveway. The first day I drove it, after returning, it started overheating. The coolant isn't leaking anymore, but it doesn't seem to be circulating through my engine at all. My mechanic said it was probably just my thermostat, so we replaced it, but nothing changed. He said he measured the temperature and it's not really overheating, but the other day it stalled on me and it smells hot and the fan stays on longer than normal. What's going on? Please help.