Why is your transmission only some times shifting hard into second?

Where is the spark plugs for 2011 Kia Sorento? Do you heat the pan or put in the oil first? How do you change fuel filter 2004 gm Yukon? How many quarts of gear oil should you put in your rear end? In what order do you connect the spark plug wires to the coil posts on a 1999 Saturn SL? Can gasoline that you use in your car cause that gunk build up on the valves like shell says it can in their advertisement on tv? What happens if charger is connected to wrong terminals? Where is the oil pressure sensor on a 1999 Mazda b2500? How do you reset the change AC filter message on a 2003 Lincoln LS? Why does the engine rev on its own when the engine is running? How much does a BMW battery cost? How do you grease alternator bearings? What are the advantages and disadvantages of pi section filter over a shunt capacitor filter? How much oil does a Briggs and Stratton 4.75 hp lawn mower need? How do you remove the passenger side door panel? How do you replace a distributor in a 1995 Toyota Camry 2.2L? Where is the transmission dip stick on a 1994 maxima Nissan manual transmission? What size socket to take out spark plugs 2.6 1992 chev s10? What is the firing order of a 1980 Honda Accord 1.8L and what is the order of the plugs on the engine? Why is a diesel engine known as a constant torque machine?