4 Wheel Drive/SUVs: Chevy Help, chevrolet k1500, jump time

Question
I have a 1994 Chevrolet K1500 4WD pickup. It won't start and sounds like it is bubbling at the tailpipe kind of like it's underwater. The check engine light was on for a while and I replaced the O2 sensor and plugs. It has not jumped timing. Can you help? Thanks

Answer
The distributor didn't jump time but that doesn't mean the timing chain didn't. This could be a little more serious than yopu think but it could be simpler too! Check everything and do a compression test to see if the valves are closing as they are supposed to and let me know what you find

Matt