Sure could use some help. my 5.7 99 Tahoe at highway speeds shudders and gets CIL for PO305 missfire.Around town and under 65mph the tahoe runs great. I've changed plugs, plug wires, cap and rotor,Cam pick up sensor, #5 fuel injector, In the meantime the fuel pump went so that and the fuel filter has been changed. local shop checked for broken valve spring, Checked with bore scope, Compression test on cylinder, they say everything so far checks out fine??? Any help is needed.