OP
OP
androu
Guest
Hard to tell, really, it just doesn't have any grunt and gradually loses speed/rpm.
It does sound a lot like a fuel starvation issue.
When it slows does it feel like one cyl isn't firing or do both quit? If only one then I'd look at injectors. (it may not be obvious that it is a single cyl dropout with the muffler on the NT, have to carefully notice change in firing frequency).
I'd also not rule out a computer/sensor problem, even with no codes.