2.3 wont heat up

I bought this car with a cracked head, and not running. I put on a used head, new thermostat, new radiator and cap, and run a 50/50 antifreeze mixture. I drive it about 25 mile one way to work everyday. The temp gauge barley touches the L in NORMAL on the gauge. I have checked it with an infared thermometer, and checked the temp on a SNAP ON scanner. Both read pretty close to what the gauge shows. Because of this the computer will not go into closed loop, and dumps tons of gas trying to warm it up. I have changed the thermostat again, to no avail. Can anyone shine a little light on this on for me? Any help would be appreciated. Thank you. Btw, it is a 93 2.3l.

I did bleed the system. (myexpreience has been air pockets cause overheating) The thermostat I installed is a 195 deg. Last night I covered half of the front side of the radiator with cardbord. On my way to work this morning, it was about 50 deg outside, the temp rose all the way up to the A in NORMAL. I was a bit frustrated. On my way home this evening with the A/C on, it actually got up to the middle of the gauge. This is what I consider to be normal. I work on cars and BIG trucks every day for a living. This is one problem I havent been able to solve. I cant remember the last time a customer complained that their car wouldnt heat up. LOL. The only thing I can think, is that the thermostat is flowing water all the time, never keeping the coolant in the engine long enough to let it absorb somne heat. This is why I replaced it the secound time. But what are the odds of getting two bad thermostats. Maybe Ill change it this weekend. Man I cant wait to stab in the 302.