If putting pcm in my 94 JGC ZJ from another 94 jeep. My jeep is 8cyl other jeep was 6cyl, Same part number. Will this matter?

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I changed pcm in my 94 Jeep GC ZJ. Got other pcm from 94 jeep grand Cherokee that was 6cyl. Does that matter? Part# was the same. Jeep started(s) right up and all problems gone. Now it doesn't seem like it's getting enough power. Like a vacuum leak. Please advise.