cooling problems

[j-13gtp]

Ok guys this past week ive been having problems with my radiator, leaking whenever it wants to. Its quit here recently, but when I got off work I came out to my car and started it up, the engine was still warm from being driven 3hrs before but outside was like 45 degree's. I get out the parking lot and the temp meter on the dash rise fast; I turned the heat full blast no warmth coming from the vents. After a short time the heat comes on and the temp goes down way down. But this doesn?t explain why for a whole 5minutes the temp was near 210 and then drops to 150 degrees.
The question is, do I have a problem with the thermostat or something else.
Maybe Im just imaging things :wtf:

[RednBlack]

Thermostat sticking

[corning_d3]

Thermostat or low coolant.. I've even had air in the system cause that.