Chevrolet Repair: 96 Chevy Impala - hesitation/sputtering, chevy impala ss, chevy impala

Question
I am having some problems with my 96 Chevy Impala SS.  Whem driving the car at low speeds, usually 15mph or less, the car seems to run a little rough.  It almost feels like a misfire at times.  I have just replaced the distributor, plugs, wires, and alternator within the last two weeks and I am still having the problem.  The car sat for apporximately two years without being driven because I was deployed to Afghanistan but I had a friend of mine start it periodically just to keep the fluids running through and he didn't notice anything.  The problem only seems to occur when in reverse and when in drive, usually before the car shifts into second gear.  It does happen occasionally in between the 15 - 20mph range at times.  My first guess as to what might be wrong was dirty/clogged injectors.  So I ran a full tank of gas through the car with some fuel additives to help clean the injectors but I didn't notice any improvements.  Now I am begining to think it may be the fuel pump or the fuel filter but I am not sure.  When the car is running at higher RPM's and higher speed, I don't notice any problems and the car seems to run just fine.  I am hoping you can provide me some info as to what might be going on.  I don't want to start tearing into something and start buying parts to replace without having a good idea of what is wrong.  Thanks in advance for any info you provide.  It's nice to see people donate their time to help others.  

Answer
When a car sits for long periods of time without being driven there are many many things that can cause this problem such as:

1. A residue buildup within the throttle bore on the throttle plate and in the idle speed circuit chambers. See if the throttle plate area has any BLACKISH residue buildup on it and clean it using a suitable aerosol cleaner spray. Look for cracked/broken vacuum lines by spraying the lines with carb cleaner and if the engine speed increases or changes when you spray a particular hose look for cracks in the hose.

You may need to take it into the shop and have NUMEROUS items tested.


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