I am at my wit's end, guys. I cannot get the line disconnected. I have those plastic disconnect set, but they do not seem to fit.
Ideas?

 

Did you try to moderately push the line toward the filter, squeeze the green tab sticking out of the line and pull the line off the filter?

 

Yeah. Eventually. Felt like a complete idiot...

 

That's right. When one of those connections finally lets go you wonder what all the trouble was about; another example of a job where you gotta "show it who's boss".
I put a whisper of silicone grease on the new filter's nipples out of respect for the seals in the connection.

Just for the record; your filter change wasn't the worst by any stretch.
Bad is when the connections break and/or the hoses collapse/kink/crack and you have to resort to a repair kit.

 

Figuring out how to do something you don't know how to do, simple as it may be, doesn't make you an idiot. Either way, we all have our moments. Good job

 

True.
did not fix the issue, though....
still having hesitation when accelerating through the gears

 

Sounds like the computer might not know where the throttle plate is. In other words, possibly a dead spot in the Throttle Position Sensor. Look up how to test them, it's a relatively simple test as long as you make sure you understand what the test is telling you.