Surging and temp problems

[wesley's mom]

I have a 1998 SL2 I am having a problem with the temp sensor (s) I am having the problem of surging while idle and while driving. I can literally watch the RPMs rise and temp gauge go crazy up and down. The temp gauge never gets over half way. I have replaced the sensor on the side of block twice (told first one was defective) that fixed it for a while then same thing starts again. Is there anything else that I should check or replace to fix this problem?

[HAWG]

check the wire that plugs into the sensor for corrosion. we usually replace the sensor and connector for that problem

[saturnspeed_12]

yes check the plug, typical for corrosion. but too where did you buy the sensor and does it have a brass tip?