i Have a 97 blazer with a 4.3 vortec motor. It has 208,000 miles and has a gutted cat and complete straight pipe exhaust. New fuel pump and filter in 2015. It has a misfire that comes in at about 1500 rpm and doesn’t really go away after that unless you floor it and it doesn’t miss. Doesn’t throw any codes either. This past March I did new plugs wires and cap and rotor. Yes I used oe Delco plugs and duralast gold wires and cap rotor. It also may be related but it keeps losing antifreeze. No leaks and it’s not in the oil either. It has a new radiator and thermostat to. I’m so lost with this if anyone can help me lead to something I’d appreciate it. Thanks.