Truck will start only when accelerator is held wide open and is really rough and shaky and will only run for a short period. I have found large amount of fuel collecting in #2 cylinder and in oil

By holding the gas pedal all the way to the floor you are shutting off the injectors not allowing them to supply fuel,this is called clear flood mode.this indicates too much fuel supply,also with #2 cylinder flooding and gas in the oil.you may want to check the injector for this cylinder,plug,wire,you may need a tune-up.change the oil as too much can cause an explosion in the crankcase and thin the oil out so much it can cause engine problems.

Hello and welcome to FixYa!

It can lead to multiple issues. If there's oil on the spark plugs then it can be caused by a worn out piston rings. You will need to have it replaced to get rid of the problem. Regarding too much fuel, it can be caused by a faulty O2 sensors which surely require replacement too.

Hope this helps and thank you for using FixYa! Have a good one!

Check and see if black smoke is coming out of the tail pipe, if so and your engine is a Vor-te you could have a leaking fuel injector or a leaking fuel pressure regulator valve, intake will have to be remove to check.