Could it be a sensor?

I have a 2003 Mazda Tribute V6 4wd.  My
engine light has been on for several months
but vehicle ran fine. I check it out when it
started to miss out.  I first received a P0306
cylinder 6 misfire. So I replaced spark plug
but engine continued to slightly miss out.  A
couple days later I got a P0305 code cylinder
5 misfire.  Next day a P0300 random
multiple cylinder misfire and a code P0396
problem cylinder 1 pressure sensor  and
cylinder pressure sensor circuit.   While
driving transmission slipped out of drive
and would not engage into any gear.  I pulled
over and noticed idle was high. When idle
returned to normal within a few minutes
vehicle went back into drive.  I slowly drove
off but within a couple minutes same
problem.  Am I dealing with sensors or
transmission problems.  Fluid is fine and no
previous slips of any kind.  I appreciate any
and all suggestions.