Don,
I gotta go do a 50 hr on the 182 today(oil,plug swap, compression test, pretty easy) ... When I get chance I'll take a look at athe source code and see if I can devine anything. *Usually* it's not the "read initiate pulse" kinda timing that causes this.. it's the total mainloop cycle time (period between read's) that starts to approch AM frequencies...
FWIW I've been reading/lurking on Karl's interferance thread. I'll post any ideas I have there...
--.- Dave