Stalling at Low/High RPM

Hi y'all,

I previously posted about a rough idle and stalling issue, and I discovered that the "new" injectors I had installed in the truck were causing it to stall when accelerating out of the park. Additionally, I found that the previous owners had installed their fuel pump incorrectly. After fixing those issues, the truck is running relatively smoothly, still experiencing a somewhat rough idle or vibration issue, but I believe the engine and transmission mounts are causing most of it. However, it has gained a new problem where sometimes at high RPMs, such as on the highway, while slowing down at a negative incline the truck will start to lose power and backfire(s) occurs, if I step on the gas the speedometer slightly rises but then continues to go down (my theory is that the old injectors are getting stuck and cannot disperse fuel), then I have to pull over. Once pulled over, I have to unplug the MAF, attempt to start the truck, which fails, of course, and then plug the MAF back in, allowing the truck to begin as though it's brand new. Additionally, the truck shut off when going over two slightly tall speed bumps. The first speed bump was no issue, but the second caused the truck to stall, despite traveling less than 5MPH over the bump. Similar to when it shuts off at high RPM, I must proceed with the MAF procedure to get the truck running again. When driving around in the city, these issues do not arise and only occur in specific situations, but I cannot understand why. Has anyone faced a similar issue, or do you have an idea of what might be causing the stalls?