Two issues
 

I have a 2010 f150 with a 4.6 50,000 miles. My first issue is when the trans is cold it sometimes shifts a but hard into 4th going up a hill (note I already got the fluid changed) should I be worried? Second issue when I drive for any were the engine heating gauge will go up to its normal temp. But if I stop cut the truck off and cut it back on it will read cold again and take it's time going back to a normal half way point. Any help or advice on both of the subjects will be welcomed

Uman, welcome to the forum. I moved your thread here, because the "comments and suggestions" section is for improvements to the forum itself. I'm sure someone more knowledgeable than me will be along to help with the shifting issue. I doubt you need to worry about the coolant temperature gauge issue. My Transmission Temperature gauge does the same thing. I believe it's just the way the sensors react through the ECM.

- Jack

In 2010 there were 2 transmissions available based upon the engine. 6-speed for the 5.4L and 4.6L 3-valve V8s and 4-speed for all others. So ... Is your 4.6L a 2v or 3v?

http://www.gdmjoe.com/icons/lightbulb.gif HINT/TIP: Put your complete vehicle information (year, model, cab, trim, engine, wheelbase, _x4 drive, mileage, etc., etc., etc.) in your signature -OR- provide it in your posting(s).
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4 speed overdrive

It shouldn't even shift into overdrive (4th) until the fluid reaches close to normal operating temperature.

You might need a new coolant thermostat, if it's stuck part way open it will take its time warming up.

So I replaced the thermostat. But the new one us makeing the temperature gauge go up and down. Did I get a bad one?

If it's an aftermarket thermostat, quite likely.

https://www.rockauto.com/en/moreinfo...444704&jsn=457

https://www.rockauto.com/en/moreinfo...444704&jsn=477