Chevrolet Repair: Start Problems, throttle position sensor, mass airflow sensor

Question
Dear Van,
  Thanks for your help with questions.  I have a 1995 GMC Sonoma, 2.2L 4 cycl. 5-speed truck with high miles.  For the past couple of weeks about one out of every 3-4 days after I start the truck up it has severe idling problems and when driving it  it will spit and sputter under a load or while taking off until it has run for at least thirty minutes.  It has only been doing this sporadically.  I changed the plugs but this still continues.  
   The truck didn't start last week so I had the truck looked at a shop that thought it might be the time or timing chain, they checked the chain and said it was okay, but said it was flooded badly after checking and cleaning the spark plugs.   The truck now won't start again.  The battery and starter are both working fine, but the engine will not turn over.    I don't know what is up with this thing.  Thanks again for your help.  
thanks,
Scott B.  

Answer
Hi Scott,
You could have poor spark due to plug wires, or something else in the ignition system. Easy enough to check with a spare spark plug clamped to a good ground. Just see what the spark looks like while the engine is running on the other cylinders.
If you have a good spark, you may be getting too much gas.
Some reasons are dirty injectors...run some injector cleaner through the tank with the gas.
A sensor loose, or bad. Could be throttle position sensor, oxygen sensor, map/vacuum sensor, mass airflow sensor.
The mixture is dependant upon accurate readings from them.
If the vacuum is low, it could be a dirty EGR valve, or a vacuum leak in the hoses.
Van