2006 ford escape

I put diesil in my 2006 ford escape and i drained the fuel line and put new spark plugs and fuel filter now my transmission acts like it is sliping what could it be.

First you have to remove all the diesel fuel. How much diesel did you put in? (Estimate as closely as possible)

Empty the gas tank completely.

Force all the diesel out of the fuel system including the injectors. These MAY have to be serviced individually.

Replace the fuel filter again once ALL the diesel is out.

You have to get the engine running properly before worrying about the tranny slipping.
I suspect because the engine is misfiring or barely running is why you think the tranny is slipping.

If I am wrong about all of this, I sincerely apologize.