fluctuating temp causing other probs??

My engine temp will get to 210 before dropping down to about 170-175, then cycling back up. Back and forth... I've burped the system repedetly, might have to go w/a Robert Shaw therm. I'm wondering if this could be causing a hard start when warm. When the motor is cold she fires up perfect. Let it sit for about 20-30 mins, it's a bear to start. Could these two be connected? I don't think it's the check valve or fuel pressure regulator, seeing as how it starts normal when cold(leading me to believe it's getting good fuel pressure). Perhaps the fuel pump is getting goofy when warm? The previous owner says he replaced the Crankshaft position sensor, but i don't know how long ago. Cam Position Sensor, maybe? Leaky injector? I'm running out of options here... Any help would be awesome.

Thanks in advance guys

'94 XJ
4.0
5spd.
181,000 miles