1998 Tahoe 5.7 PO300. NEED HELP PLEASE

bobradley4 · December 31, 2015

Hey guys. New here. First post. I am a technician and am working on a 98 Tahoe. Came in skipping. Only code it has is a po300. Pulled distributor cap off and noticed badly worn so went ahead and did full tuneup. Cap, rotor, plugs and wires. Still skipping. Running no rich so I looked down into throttle body and noticed a raw fuel smell and gas soaked. Pulled upper body make and the spider assy was leaking. Thinking I had it fixed? Nope. Still skipping. By this time I'm stumped. Compression test on all cylinders were good. Leak down test was good too. While engine is running I can take cyls 5,7,6&8 wires off and no change in the way it's running. So apparently it's only running on 4cyls and it being the front two cyls on each bank. I thought about shimming the crank sensor so I bought one and shimmed it with the provided shims. No change. New distributor. No change. Pulled the valve covers to check rocker arms. All good. I know I'm getting fuel because the plugs that are misfiring are wet. I know I'm getting spark per spark tester. I took exhaust off and no change. The vacuum gauge fluctuates pretty bad at idle but I assume it's because it's only running on 4cyls. All injectors are getting a reference signal. I did the crank relearn. Nothing. What more can I do? Any help is greatly appreciated.