Every once in a while I would go to start my 90 lumina van and there would be no spark and no fuel.I would go back a few hours later and it would start right up,but run a little rough.It now has gotten to the point where it will start while I am turning the key (I have to pump the gas sometimes) and rev up while I am turning the key but as soon as I let the key go it will stall,and now sometimes it will stay started but run very rough.I have replaced the ignition module,fixed shorts,replaced wiring that looked bad,replaced a pigtail that was no good going to my map sensor,replaced plugs and wires.I have distributor that is about 3 years old.Replaced the fuel relay recently.The fuel pump is 1 year old,the fuel filter is also 1 year old.I have no codes when I run my code reader.I am lost,any ideas?

Sounds like a bad ignition SWITCH under the steering column. Not the key lock cylinder but the switch itself. I've seen this problem before on GM vehicles...