Downshift caused backfire then broken engine

[Rwillia4]

Took the car out for a quick spin, nothing hard, started fine, warmed up a little at idle then cruised to the highway. The water temp was coming up by the time I was on the on ramp. Jumped on the highway at a casual acceleration came upto 65-70 mph for a 3 miles then got off. Came to a stop at a stop light, left casually when it turned green only to get stopped by the next light 300 yards down. I downshifted the car backfired out of the exhaust (it does this sometimes but I thought it was an exhaust leak) This one sounded different. As I came to a stop at the light something was not right out of the right bank. Engine noise at idle is the same, bu there is a strange sucking sound coming out of the exhaust, like an exhaust leak but not a cracking sound more sucking. I limped it home ~1 mile. I didn't get on it to see if I am down on power but something is not right. Any ideas?
I opened the hood at idle and it looks like some blow-by might be coming out of the valve cover breather (but I'm not really sure).
The engine only has 1400 mile on it and less than 40 hours of run time. I guesing a stuck/bent/not working valve BUT I don't know...

...man it was suppose to be a simple cruise!!