please help.Car looses power when acselerating and picks up on higher rpms, feel a little like engine is choking.

 

could be 100 different things need more info

 

Yes. sorry for not giving enough info. I owe two mercedeses S420 1995 and 400E 1992, I love both of them but sinse they are older cars they requier more work. It would be very helpful to be able to read codes myself. S420 is a family car I have done a lot of little replacement work. I do everything myself( do not have anyone i can trust my car). now i am replacing engine and transmission mounts it made my ride so much more comfortable. the thing that worries me is that the car( specially driving in hot weather) does not heve power, I push the pedal it does not pick up untill gets to higher rpms. then driving back at night on cooler engine its is much better. Maybe lazy transmission when very hot. What is kick down relay? sometimes it feels like choking.