The van

my friend has a 1994 chevy 20 . its got a 350 motor . conversion . when you first it up it run good . after it get warmed up it both runs hard or dies . we have have a tune up with plugs,wires,filters, . and the guy 's that looked at iyt put it on a dino and say that they could not find any thing wrong , but when they drive it did the same thing . they pulled the plugs , and fine a lot of gas in the conbustion chamber s are over full of gas . any help or idea’s would be greatful taken , thanks

Some more info has to be provided. Conversion to…? Has it been converted to a carburetor or is it still running fuel injection?

He almost certainly means it’s a conversion van, with the high top, television, mood lights, etc.

Sounds like leaky injectors to me, but that’s just a WAG from the description.

Fuel system problem perhaps?

Flooding the cylinders when hot. Bad fuel pressure regulator and/or injectors? Coil pack(s) breaking down?