hey guys... ive got a 90 gmc sierra.  about 2 weeks ago i changed the fuel filter, plugs, and plug wires, and the air filter.  it ran good for about a week then it all went bad.  it idles a little rough and when i am cruising at a steady speed and am just giving it a little gas it starts to kinda cut out.  i dont know what the problem is.  also sumtimes if i drive it the shut it off and try to turn it back on it barely cranks.  i have to let it sit a while then start it.  is it the ignition coil maybe?  or just a miss in the plug or wire?  help please, no one can seem to tell me what it is.