Ford: 1993 Ford F150 5.0 V8 Auto Tranny ROUGH IDLE, new distributor cap, throttle positioning sensor

Question
Dear Sir,

I have 93 Ford F150 5.0 V8 Auto Tranny. It has 117,000 miles on it and is the best vehicle i have ever owned. The problem is this, it has a horrible idle for the past three months. It chugs, sputters, goes into a high idle, then almost dies. I had the fuel filter changed about a month ago, new plugs and wires two months ago, new distributor cap and rotor, new PCV, and I have run the fule injector cleaner through both tanks. When I got the truck, it had not been well maintained at all, the cooling system was a gigantic mess of what appeared to be mud and water. I put in a new radiator, all new hoses, flushed it, new heater core, new thermostat, new fan clutch. I have no idea why it is idleing like garbage, it even chugs while driving every so often (probably 3 out of 10 times). I have noticed that the serpentine belt can be moved up and down with over an inch of play either direction, and with a little pressure the tensioner can actually be moved...could this be the problem? A bad tensioner that is not putting enough pressure on the belt? I also notice that the temp gauge flucuates ALOT during these times which also leads me back to the belt (I put in a new coolant sensor also). I took it too a repair shop and they wanted 100.00 to diagnos the problem and said that I probably needed a new computer, idle air control, throttle positioning sensor, MAP sensor, and a new belt and tensioner becuase the belt was somewhat frayed on one side after being replaced only 6 months ago, and a new power steering pump because mine has whine to it and is "causing strain on the engine that can damage it". They quoted me over a 1,300.00 to do all this...can this possible be true? No lights are coming on on the dash and I had my alternator checked by Auto Zone 3 months ago and everything cam back good. Anything you can do to help advise wise would ve very much appreciated before I go and drop that much money to these people. Thank you very much.

Best Regards,
Barton

Answer
Barton what i would do before you do any thing else . go to your nearest auto zone have them see if you have any codes  they do it for free then let me know what they are and we will take it from there.to me it sounds like there guessing .let me know