Surging doesn't have nearly as much in power?

Hello,

There are few reasons for an engine to surge.
It could be due to faulty spark plugs, fuel pressure issue or vacuum leak.
The best course of action would be to take a look at the possibility one at a time and figure out by deduction.
Vacuum leak is a very common reason for surging. Check for any cracked or broken vacuum hose.
A vacuum leak can also happen due to leaking intake gasket. Which can be tested by spraying carb cleaner at the base of the manifold. If there is a leak the engine will react to the carb cleaner and will idle higher for a little bit, then go back down after the carb cleaner burns of.

Here is a helpful guide on typically reasons for engine surge:

https://www.2carpros.com/articles/engine-surges

Please let me know if you have any questions.
Thank you.