Re: P0300 05 Jeep Grand Cherokee
Coil packs and injectors rarely fail. Usually it's something like a cam or crank sensor, a bad ground somewhere, or maybe a poor connection on some component(s). Have you isolated which cylinder(s) are misfiring? Is it the same ones all the time? Does the misfire occur right from initial startup, or after it reaches a certain operating temperature? When it occurs, is it continuous or does it ever "smooth" out?
05 LX/RT & 06 WK/GCO, modded similarly, MDS "ON" Light, Vortex Gens, Debadged, DashHawk, BT Catch Can, SRT CAI W/Add Air Inlet, K&N Filter, Sonnax Trans Press Booster, SC Tuner W/Adv Trans Tuning App, DS Tuner, Cust tube headers w/3 in. catback, Bilsteins, SRT frt/rear bumpers, Eibach SRT Lwr Sprgs & Sways, FRI Sidewinder Cam Adv 2*, 6.1 valvetrain, SLP 25% UD Pulley, BBK 90mm TB, SOS Coils/.060 plug gaps. 20 in. SRT Reps.