You said you changed the terminal clamps when you put a new battery in, I would pay very close attention to where the cables go into those clamps and check to make sure they are clean tight and making good contact, I don't trust those aftermarket clamps it is best to only use battery cables that are soldered to the clamps. When I was much younger I put a set of those on a Mercury Cougar that I owned, I thought they were tight but ended up melting the negative post off the battery because they were not making good contact. I learned a valuable lesson from that and have never used them since.