Have a ML 430. Was stuck in park. Shifted manually, but the car does not shift right between hi-lo

Those check engine lights are there for a reason, next time one comes up take it somewhere and get the code properly read. Part stores usually have a scanner they lend for free. As to your problem I'm not exactly sure what your problem is. It was stuck in park? So you shifted manually? Didn't they all have a 5 speed w/ overdrive auto tranny? If it was stuck in park, how did you shift it? The fact that it keeps dropping into a lower gear, sounds like the linkage needs adjustment or a 'limp' mode, I don't know the car well enough to say for certain, but you should take it to be properly diagnosed. Hopefully that check engine light will come back on and the code can be read.

Thanks. By manually, I meant I was able to unlock it by physically placing a pin below the gear shift per the manufactures manual.