I have a 1988 Jeep Cherokee, when I drop it into drive it acts like it has no power, but when i drop it into 2nd or low it seems to run fine, I did find what I think is a vacuum line coming off the transfer case and traced up behind the motor, but were it connects to is a metal tube, but there is nothing connected to the otherside of the tube, can anyone please let me know what it connects to. Thanks

I’m wondering if that hose connected to the transfer case is just a vent hose. In that case the other side of the tube (or the metal tube to which is connects) should indeed just be open to the atmosphere. Does that hose connect to the transfer case at or near the top of the case? If so that would be consistent with a vent.

Back to your original problem, when my Ford truck developed that exact symptom, while I didn’t know it at the time, I was two weeks away from making an appointment with a transmission shop for a transmission rebuild of my C4 transmission.

Suggest you double check the transmission fluid level. If the fluid level is ok, I expect you are looking at a transmission rebuild. Eventually 2 and L won’t move your vehicle either.

Assuming it is the transmission, it is possible it is something simple too, like a faulty solenoid. Less likely on a 88 than a 98 though. Or you could just need a proper =transmission service, dropping the pan, cleaning it out, replacing the filter, refilling with fresh fluid.

My first thought was a vent tube too, but I lack the depth of knowledge on these necessary to provide a definitive answer.

OP, can you get a photograph?