01 Impala 3.4L Cooling and Trans. issues..Need Help!

I have a 01 impala 3.4L V6 with 162k miles on it. It has been a good car for a long time until recently, before the car had green anti freeze in it and shop recommended dex-cool so i had it changed and 3 days ago i noticed my water pump was messing up so had it replaced and it was fine gauge stayed below half just a notch or two above a quarter til now it goes a notch or two past half and also it seems hotter than normal to me. Just today my transmission felt sluggish and sort of jerked/ hard shifted between 1-2, 2-3 gears. need some help on what i should do... weather i should flush radiator back to green anti freeze coolant...and also if this could cause my car to overheat and transmission to act up??? i was told to try changing anti-freeze, sea foam my engine & put trans tune in transmission... not sure how those suggestions are so looking for more opinions and advice..

thanks,

sam

The coolant has nothing to do with the tranny except in many models they both share the radiator for cooling. Check for oil in the coolant by looking in the coolant reservoir for oil floating in the coolant and transmission by checking the dipstick for droplets of coolant in the tranny fluid, if you don't find anything it's probably not the cooling system. Aftermarket pumps often are not up to factory specs and either flow too much or too little so just the temp being a little off is not something to worry about unless it was normal after the pump replacement and then after a week of driving it started to creep up. The transmission going could result in higher coolant temps as could the cooling system thermostat starting to go. Have the transmission checked by a professional preferably in a different shop than the shop you have been going to as there are too many problems in such a short time from going to the shop that did the coolant change.
Additives are generally not a good idea.