Ousten Pruitt

Ok yall need some help. 98 c1500 5.7 131k miles very very bad misfire and almost no vacum at idle to the brake booster. I've pulled the intake and cam and lifters are all good no wiped lobe changed the updated mpi out with a new mpi again newer plugs less then 15k on them new cap rotor and plug wires still have a bad misfire, was moving from Jonesboro to bentonville arkansas and midway in Conway I saturated running real bad it's always had a misfire under load on cyl#4 haven't run a compression test but there's only a gallop on 1 cylinder and has always been like that it flooding out 2 or 3 cylinders and I'm stuck idk where to go have the distributor set correctly using a scan tool what should I look at I'm gonna pop the y pipe off layer and see if I have a clogged cat but idk any inside would be helpful thanks. I don't have any egr codes if someone could give me the values for sensors I should be looking out for to see if mabe a o2 is going bad toss me the values and I'll see what myne are at thanks Screen_Recording_20240628_120755_Facebook.mp4