My truck has a 3

My truck has a 3.9 liter V6 has difficulties shifting between gears. It looses power and acceleration when floored. It used to only happen when going over 50 mph, up hill, or in crusie. Now its starting to do it between first and second gears as well. The codes have been different at every place Ive taken it. When it first started the codes were related to the camshaft sensor and o2 sensor and were erased but did not help. Now the code says leak detection or mechanical fault and I was told to have my solenoids replaced.