hey guys i have a 1964 massey 65 that is running like crap. i bought it last year after it had been sitting for 10 years changed all the fluids and rebuilt the carb and did a tune up right away. fired it up and within a few minutes it was pouring oil out the bellhousing turned out to be a bar rear main seal so i replaced the clutch and all the seals on the trans side also. right now it will fire right up and idle fine for about 5 mins then it starts backfiring out the exhaust. it doesn't seem to be random almost like it's every time a certain cylinder fires.after it's fully warmed up it stops backfiring but seems to be lacking power i've been running in low 2nd any higher gear and it wants to stall out. it had new rings before it was parked for the 10 years. i was thinking somthing going on in the head but just did a dry compression test and had 100-110 on all cylinders. i had replaced the plugs last weekend and ran it about an hour but noticed today that 3 of the plugs have soot or carbon on them and the forth still looks like brand new. i double checked and all cylinders do have spark. does anyone have any ideas?