1991LX5.0

After i finished my H/C/I swap i took the car out for a test drive before i got it tuned to see if there were any problems. The car got really hot and had to pull over a couple times to let it cool down. On my way back home i stopped and got a 160 degree t-stat and installed it when i got home, burped the system and took it back out. The temp guage always hovered right around 1/3 of the way up the guage but for some reason the low coolant light always stayed on. When I had it tuned the guy told me there was air in the system so he burped it but when i drove it around it got very hot all the time again but now the low coolant light was off. So today i burped the system again and it seemed like he put alot of air into the system and i got it to stay right around 1/3 of the way up the guage again but the low coolant light came back on and i cant get it to turn off. Any ideas what it could be?

By the way the car has the stock radiator with a black magic electric fan wired to turn on with the ignition