I've already replaced the engine a year or so ago.
It's not misfiring biut it's down on power and vibrating quite bady.
I drove another P38A yesterday and it's smooth up to at least 5000 rpm. Mine vibrates at idle, then smooths out a bit then from about 2700 rpm it gets really, really rough like it's badly out of balance.
If it wasn't down on power. I'd suspect something else.
Ron

