intermittent overheating???

okay i have had my 1991 mazda mx-6 Turbocharged for a little over a year....

normal operating temp has usually been around straight up n' down,

but over the past couple weeks... it was been getting close to the H.... it will get close, then fall off some, then get close and fall off some, once it passes normal op temp, it won't go back until you let it cool down. but it will just randomly start running pretty hot, getting pretty close to the H and then it will go back down to about a 1/4 way between the half and H marks....

any suggestions on what it could be????

coolant level is good and the fan is operating....

and obviously, it runs a bit hotter at lights and in drive thru's but it will cool down jsut a bit when i do 70 on the freeway... help me out PLEASE

thanks guys....
i look forward to getting to know all of you

btw my name is nick