Internal engine cleaning?

So the good 'ol 185k 318 in my zj is getting tired and I need to try and keep her going for as long as possible before rebuild due to current financial situation. Need to do a tranny flush. Wondering about cleaning sludge an carbon deposits out of the motor and best way and chemical to use. Also wondering what you guys think about doing it in the first place. Worried that cleaning it out my dislodge something that's "plugging" the motor from something worse happening. Have been siting on a bottle of seafoam for a while now debating this. Figure might as well ask you guys that have a lot more experience than I do. Thanks in advance :-)