2000 Mercedes Benz ML430 Car Over heats normal while in idl

Hi my car over heats normal when in idle or driving. I have replaced the radiator fans and the engine fan clutch. It has enough antifreeze and everything else. I think it started when my MAF went out and I replaced it with an aftermarket. But that didnt work out right either because the engine would not recognize it it would turn off the check engine light off but the car would over heat and the fuel to air mixture was way off that it even cracked my CAT converter. After I drove the car for a little bit with that MAF sensor the car would overheat and shut off. Then I bought a factory MAF and put it in the car ran great but the engine does not stay at normal temperature it just goes up and down. If I park somewhere and stay at idle for a minute the engine temp rises when I start driving it goes down and I cannot figure out what the problem is.