Different engines. Same ecu. A lot of the possible causes would have been swapped with the engine. The harness is the same though. Different maf. New tps. Bypassed knock sensor. Different cas. The more load, the more apparent the missing becomes.
You can shift to a higher gear under heavy throttle and it'll loose power and break up until the rpm's get to 3 grand and it's like a flip of a switch. It smooths out and pulls hard all the way to redline.
If you drive like a racecar all day with the rpm's up high, you'd never know there was a problem.