1990 Trooper 2.8 and manual trans problem

I just aquired my 2nd trooper(first was a 4 cyl 87) and I am slowly getting it into shape.2problems,first,how to reset the flashing check engine light.Is it a switch I need to look for or a screw? Second issue is a 4wd problem. When I put the beast into 4wd,all seems fine until I start to move.It seems as if the brakes are on,and when i put back into 2wd,it really feels like the breaks are on.I must reverse for a bit, and then it frees up no problem. I am going to look at the front end this weekend,just wondering if anyone had any ideas.....The hubs are automatic, and are on my list to replace asap........Thanks, Tom