Engine surging

OK here's my problem.
When I drive through the small town I live in I hardly ever exceed 35mph as thats the highest speed in the town, I do occasionally get my car to around 70mph for short bursts to get to work out side of town.  Today I was driving on the freeway cruising at around 65-70mph and my engine started surging, the RPMs would drop by 200-400 rpm. I did notice that my coolant temp on the intrument cluster kept flashing lo and would jump between 55* 112* and everywhere in between ( yes you read that correctly ) once I got off the freeway I took a hard left turn and my coolant temp jumped back to around 180* and stayed there. Could there be any relation to the 2 problems? my coolant level as fine when I checked it. so could it be a coolant temp sensor? or maybe my tranny (4L60E) clutch is slipping?
 

it sounds as if the coolant sensor is bad. it's located by the number 6 plug. it should be about twenty bucks. with the sensor being bad and jumping around like that the computer is trying to adjust everything because of wrong info being sent. a new one should do the trick.

Ok! I will check that out! :-) Thank you in Advance! 

Could be that the ECM is seeing the temp fluctuate, and is releasing the lock-up clutch in the torque converter. The ECM needs the temp info to determine if the engine is warm enough to engage the converter clutch.. If the temp sensor reading is jumping around like that, it WILL engage/disengage the lock-up.
The sensor for the temp gauge itself is a different sensor than the one used by the ECM, tho...I think. I'd have to check the wiring diagram...
Adams' Apple2010-10-06 19:50:46

i think it is the same joel. a friend with ann 88 had a problem with his dash guage and car acting screwy. changed the sensor by the 6 plug and car straightened right up. as you say tho, with these computers in cars it could be anything.

Hey guys I checked it out and the connector itself was broken, well at least one of the wires to it had broken, I replaced the sensor anyway but that doesn't matter until the connector is repaired, any suggestions on how to go about fixing that? the connector is in a very tight spot is there anyway I can pull it through under the engine to work on it? 

Replaced the switch, will try to work on connector when I have another day off

you may be able to buy a replacement pigtail at an auto store and splice it in. guess you would have to see where the wire is routed.

Sounds like a plan :)

Ok so its the Engine Temp Sensor that I replaced, I believe the sensor itself was good but the connector was bad, I replaced the sensor itself anyway, but now have to find a new connector with pigtail, any suggestions on where I can find one?