OE tstat is 190 I believe. The cooling system seems to get trapped bubbles when you mess with it and folks have to burp it a little to get them to clear. Even without the heater core it should maintain a temp right around 210. Flush is the best I can get you and make sure the stat was installed in the proper direction. Check your mech fan and clutch also.
89 2.5 TBI, 4" RC lift, 1" Booms, SYE, Adams Driveshafts front and rear, Ford 8.8 with 4:88s, BFG 33X12.50X15, and a ton of other stuff.
AF Jeep Club Tail Number 184