Ive had it do both and yes I ran some Techron Injector cleaner through it.
When it surges its like a clogged pipe that opens up abruptly, and the shudders are more so a transmission slipping feeling.
Dont know whats left. This morning...no problems at all. Its more often than not, but just odd.
Going to change plugs I guess this weekend. Im sure they are due, but curious if something else isnt happening internally that might be catastrophic later on.
