temperature issues

[mwellsasu]

I have a 1998 S10 extended 5 speed 2.2L. I have recently replaced the thermostat and water pump. Lately I have noticed I have been getting horrible gas mileage and the truck is sometimes difficult to start. Also sometimes when I am trying to accelerate the truck will act sluggish and kind of lurch forward some. I took it to Advanced Auto Parts and they put their little diagnostic tool on it. The man told me that the engine was not heating up enough. I always knew that overheating was an issue, but not under heating. I also noticed that when I replaced the thermostat, there was some corrosion on the thermostat housing as if there was a leak in it somewhere. Could this be the problem? A relative of mine told me that the problems I am experiencing could be related to a cold temperature sensor. Is this sensor part of the housing? Any help or suggestions will be greatly appreciated.

[VJL]

The engine must heat up within a certain time period to keep the PCM happy.
The engine must heat up to it's proper operating temperature to insure proper combustion. If the coolant temperature sensors are telling the PCM that the engine is cold the PCM will feed the engine accordingly.

Make sure that the thermostat that you put in is the same range.

If it's supposed to have a 195 degree thermostat don't but in a 180 or 160 degree.

Make sure that when you refill the coolant system there are no air pockets, propbably not a problem on a S10, more of an issue with vehicles where the engine is taller than the radiator.