jblueovalfan23

hey i'm new here, typically i'm the guy to answer questions more than ask. this time though i'm unsure. i've always done ford and dodge vehicles. my new truck sorta, got it in the spring as a project truck is being difficult. been working on it here and there, in no rush on this thing. it's an 06 gmc 2500hd 4x4 with a 6.0, sorry. it was a mess when i got it. it was sitting for rusted fuel lines on the pump for about 5-6 years. it could have aged better while being neglected. the fuel pump assembly is new, brake lines, o2 sensors exhaust (someone stole the cats) i put some used rubber on it, intake gaskets and plugs/wires. i'm not touching the rust till i get it going right but that also needs attention. the only code i'm seeing now is a p0300. it's pretty obvious when running that's it's missing but tracking that issue down is another. the gaskets and plugs/wires were throwing money at the undiagnosed problem knowing that they would be an issue sooner or later. the plugs were obviously not burning fuel, black and sooty. both guesses did seem to slightly help it. it's almost even driveable at this point. i did also use a cheapo spark tester from harbor freight. a 3 of the 8 coils barely lit it up. i'm thinking they're toast but i was wondering if there's a way to test these things with a multimeter. google was no help here. to be honest, i'm not sure the issue is even ignition at this point. i know it's getting 60psi of fuel pressure, tested that. i can hear the injectors working with a stethoscope, which means only that they're trying to work. i haven't done a compression test but it did feel like it had good compression turning the crank. i'm normally pretty good at this sort of thing but this time, i'm unsure. tried unplugging various stuff to see if it made a difference to help sort the problem and sprayed carb cleaner all over to try and find a vac leak. i'm out of redneck tricks to find problems at this point. any suggestions would be greatly appreciated. if this helps, here's some freeze frame data from my crappy reader. i'm not sure what to make of that but the long fuel trim i think is way high. i've also got just enough to run the truck in the driveway. i'm going to dump in both my gas jugs in a day or 2. don't trust it to the gas station at this point and the caliper is stuck, also on the list.