After engine swap the car will not accelerate past five MPH?

Hi,

If you place it in neutral or park, does the engine rev normally? Also, have you scanned for diagnostic trouble codes?

If you haven't checked for codes, that is where I would recommend starting. Actually, I would suggest scanning the can-bus.

CAN stands for controller area network. Basically, the different modules are tied together via a few wires. This type of scan will retrieve codes regardless of the module storing a code.

Here is a link that explains how it's done:

https://www.2carpros.com/articles/can-scan-controller-area-network-easy

Also, when it is running, let me know if there are any odd odors from it or sounds.

Let me know.

Joe