the car uses no coolant ,replaced t stat water pump ,bled system when driving

went to red on last drive and let off the gas and went back to half on temp gauge ,does computer hold gauge in half position? doesnt appear to be overheating coolant just on gauge

went to red last drive and let of the gas and went back to half and continue on,does computer hold temp gauge in half position?

no sounds like air pocket or no circulation thru radiator. have you double ck'd the coolant level since driving?

yes its good.temp sending unit is on the left side of intake manifold?

did you have this issue b4 you repl water pump? if so ck for blockage in radiator

yes just started out of the blue ,so i replaced the t stat ,and water pump and bled the system and still does it ,but the coolant doesnt appear to be overheating just the gauge

Air pockets will cause many funny symptoms , do you have an infrared thermometer? Does the radiator cooling fan cycle properly?

idles fine temp stays in middle ,going 50 or 55 mph will shot up to red take your foot off the accelarator and drops back to middle

Radiator is clogged. After it is fully warmed up , shut it off and check for 'cool' spots in the rad. core.Is the T-stat you used aftermarket or factory? The more you narrow down the symptoms timing, it's sounding more like a circulation problem to me.I think globalhelper is right.(Go Greg!)