2002 Mitsubishi Montero sport xls 3.5l 4wd - TRANSMISSION GETS STUCK IN REVERSE.
 

Hello so the other day I was driving and I managed to drive my car all the way to Jamestown back by no problem but the rain next day in City I noticed that when I was waiting from the light in drive still I noticed that the light when the light turns me and I try to go and automatically I start to go in reverse and I didn't notice that I'm in reverse gear I don't know how or why it switched one at the bottom it still stayed in the drive here but now it was showing reverse and every now and then it gets stuck in reverse what can be the problem it could it be dirty oil or what I already checked the codes it said it was an open inhibitor switch but the inhibitor switch is fine I did notice the oil is dirty though and also when it's in drive it feels like it takes forever to to go like it lags a bit I don't know what else to check. Could it be only just a transmission flush or what