Hey y’all, first post here so bare with me!

I’ve got a stick shift 2010 mini base model that I bought with a blown engine, owner left it in 1st gear while towing🤦‍♂️ spent the summer putting in a “new-to-me” engine with 70K miles on it and pretty much replaced everything else in the engine bay, fires tend to melt things…

Anyways, I’m having issue with the throttle. I can’t seem to maintain any speed under 31mph in 3rd gear without the car becoming dodgy and bucks. This is anything at or below 2k rpm’s. I can accelerate smoothly at these speeds/rpm’s but I can’t maintain any speeds in that lower range. I’m aware that those speeds are mainly for 2nd gear, but I’d like to be able to utilize 25-30mph in 3rd at a constant speed, just gets annoying goin through downtown always having to stay between 31-35 so It doesn’t buck on me. This issue is also what I believe to be linked to my cruise control issue. I can turn on cruise control indicated by the dash light, just won’t initiate😕
Maybe to better understand, almost seems like there’s a certain dead space in the pedal at those speeds and it gets confused. Once I feather it a little more gas it seems to surpass a threshold which is why it can at least accelerate through those speeds just fine.

There’s been a lot of parts, time, and money invested in this car and as to the parts that I can think of that would relate to such an issue have been replaced.
(1)throttle positioning sensor
(2)MAF sensor
(3)accelerator pedal
(4) fixed 3 vacuum leaks
and so forth

Yet I still have codes for throttle accelerator positioning sensor input voltage to high, and some adaptions along with that.

any ideas on whether I’m missing something there or input on what it may be?? Any feed back would be most appreciated as after many months of fighting countless other issues I now only have those one that remains, otherwise the car is great!

thanks for taking the time to read this y’all, hope we can get it figured out together!!