2003 international dt 4300 automatic med truck will not shift correctly

took to a mechanic, said trans is good, looks like your gauge cluster might be going out.
says rpm on dash to his computer are off. Think that might be the issue?

 

When shifts gears,first gear is good, second is ok, third, have to get about 2800 rpms and shifts then fourth the same. and does not shift hard like it has in the past. no power at all Have to stay at 25 to 2800 rpms just to stay at 50- 55 mps on level road. goin up hill is no good,
I changed out the cluster Gauge and nothing changes,
Is there some solenoid that might have gotten wet when we power washed the engine?