I have no idea why but I've went through three thermostats in 2 years and less than 6k miles. My temp gauge reads normal at idle but when driven it cools down and adds fuel because it thinks its cold again. I have been through a 160,180 and a 190 thermostat, every time i change thermostats it reads and works fine for the first month or so.Does anyone have an idea of whats going on?

Check the coolant temp sensor as well. Try an oem from Mitsu thermostat and see how long that lasts.

My temp sensor is oem from the stealership not to long ago.

Have you flushed your coolant system out yet. Maybe you have some nasty corrosion stuff going on.

How would you flush it? And it is brown from before. What does the corrosion stuff have to do with the temp?

It can clog your thermostat and water pump making extra strees for the whole system.

New waterpump as well, the shop i had it done at never told me anything was wrong with how it is, if its dirty why would it run colder?

Not if its dirty it will run colder but if its dirty and has random particles floating in it, then it can damage and/or wear out cooling compnents faster. Did you reuse the coolant? When you put in the new thermostat and new water pump did you not flush the coolant then? If the coolant is brown then you may have some issues causing damage to the springs in the themrostat.

I did not reuse coolant, The shop I had it done at replaced the coolant and water pump, I do remember before I switched the motor out, I used an old waterpump that failed on me and the old motor had rust of something in it and I never cleared out the radiator. Whats the best method to flush the entire system?

Are you using an OEM thermostat or some aftermarket one? The OEM ones are best.

What's brown? The coolant? Not suppose to be brown

Take it to a garage and have them flush it properly and have them use a solvent.

You need to get the system clean. If it is turning green antifreeze brown, then you need get that taken care of. If you don't, it will prematurely wear hoses, t-stats, pumps, seals, etc...

The af is brown, ive had two fail safes and an ac delco thermo

Coolant info here >> click