questions regarding MAP sensor, 5.4L
so ive been having some issues with my transmission, power and and MPG, and a good friend of mine who is a diesel mechanic says it may be a MAP sensor issue. is there a way to test it? the problem im having with the transmission is that it seems to be shifting too high, and when cruising at 65mph or higher and you let off the gas, it seems to down shift, almost feeling like an engine brake. im also experiencing a lack of power, which could be attributed to the transmission or the fact that i have 178k miles and an O2 sensor code which im still tracing. he also mentioned using a thicker oil to remedy my lifter knock. any inout on these is GREATLY appreciated.