number 4 cylinder not firing
 

i have a 2009 gmc 5.3 just changed actavation plate replaced all the lifters had number 6 cylinder was only one had problem before replacing the lifters an plate now number 4 cylinder got spark valves are opening an closing got compression 150 lbs. got power to injector checked with noded light tester i'm going to try right now switch injector with another cylinder . spark plug soaked with gas ! just switch number 2 an 4 injector no differents number 4 still not firing got no idea whats going on took valve cover off again an checked rocker arms there not to tight cause when valve closed rocker arm will wiggle on the shaft ?