I cleaned my solenoids a week ago @ 80K miles, purely for maintenance reasons. Thanks to ENINTY for his advice how to do this.
Took both bolts out, then removed both solenoids, marking the top one with a cable tie so I knew which was which, and after cleaning, installed both solenoids before the bolts.
I cleaned with MAF cleaner, it cleans oil and dirt, and is plastic safe. The way I cleaned them, the cleaner poured over the plastic connector -- I didn't want to break what wasn't broken.
I set them in empty oil qt containers to drain the remaining oil, they have a hole in the inside end (I did all this while doing other work on the car), blew them out with 50 psi of shop air using an old 1 gal water container with the top cut off to control the spray, held them connector end down, and sprayed MAF cleaner thru the hole in the end with the spray extension, held them that way for 30-60 sec to dissolve the oil in the mechanism, tipped it over to drain the cleaner and hit it with air.
I did this another couple of times, the first time, the cleaner run brown when tipped over, the other two, clear. Let them dry thoroughly and reinstalled in opposite positions.