98 Cavilier temp guage problem

I was out earlier and noticed something strange with my temp guage. As I climbed a hill I saw my temp guage was below 100. It cought me off guard so I let off the gas to pull over and I shot right back up to around 150 or so. I kept going and kept an eye on it. Every time I mashed the petal the guage would drop, Let off and it would come back up. It appears to be something with the vaccuum system, because I can make it flucuate a little by changing the heater knob position. It allso dropped as I downshifted going down hill. I have no idea how the temp guage could be affected by engine RPM or is connected to the vaccuum system. What could be causing this? With the speed of the needle movement there is no way that the guage is giving an accurate reading. If that were true, the engine would have to drop 50 deg. in under a second, and then regain that heat in another second. I know the thurmostat isn't stuck open. I can feel the car warm up in the morning, I get heat in under a minut. I haven't had any other problems with this car before. I am lost. Thanks.

I found the problem. There was a broken wire in the connector to the temp sensor. The movement of the engine would break the connection, and then reconnect itself. I changed the connector and all is well, escept now I have the engine check light on. I hope after a few cycles it goes off, I am due for an inspection by the end of the month.

I found the problem. There was a broken wire in the connector to the temp sensor. The movement of the engine would break the connection, and then reconnect itself. I changed the connector and all is well, escept now I have the engine check light on. I hope after a few cycles it goes off, I am due for an inspection by the end of the month.

disconect you postive battery cable or on the driver's side inside your car remove the "ecu" the engines computer fuse... that sould turn off you "cel" check engine light off. but wait 10sec when dissconecting the fuse or the cable