97 Wrangler SE 2.5 loss of power

Hi everyone! I am quite new to Jeep, but I've been around quite a few GM's. My problem is the jeep I have now stumbles upon starting sometimes and other times it starts fine. It has 160k on it now. I've replaced the plugs, cap, rotor and rotor button, along with the pickup under the cap. I haven't replaced the coil just yet. I know that the 2.5 aren't power houses but on an open highway with a slight uphill grade I'm having to drop down to 3rd gear. It has 235/75r15 tires on it. Occasionally it will stumble under normal driving conditions (when I say normal, it very rarely sees 4 grand). I figured this would be the best place to ask if I had any questions. There is no check engine light also. Anyone have any ideas? Any help is greatly appreciated!!!!! Thanks in advance!