Loss of power
 

I'm having an issue with loss of power on acceleration. Jeep takes off fine but when I get3rd gear it loses all power. It'll also start to buck around 35-45 I dnt knw if its a second issue or another symptom of the same thing. I drive an 87 XJ auto trans with a 4.0 inline 6. I've replaced several parts that were bad: TPS, AIC, fuel pump, fuel pressure regulator. If anybody can help me figure this out I would appreciate it. Thank you