Ok, i posted another post, but i thought i would regroup everything and start fresh. (thank you to those who had posted and helped in the other post) It's kinda long, so bear with me if you kindly would.

I bought a 93 f150, 5.0 this past wednesday, and the truck was sitting since june in the guys back yard. the problem i am having is that the truck idles kinda funny and sometimes dies (jumps up and down from 600-1000, sometimes below 500) and it was only doing this after it would kick down on after i started it up, then would go away. Now it seems to be doing this everytime i let it idle. I pulled codes and they turned out to be 3 digits, coming out to 126 and 173. which i believe were a running lean code and a disconnected/ bad map sensor connection.

I replaced the map sensor, and it is still doing this but no more check engine lights like before. I was told to try o2 sensor, possible egr or idle air control. Would these be the same fixes as when it was just a cold idle problem? what do you guys think?

there is a small exhaust leak on the passenger side, i believe it is after the manifold but not 100% sure, could that cause an o2 problem? I'm not 100% sure on the cause and really don't feel like replacing those 3 sensors and still not have it work, or 1 fixes it and i still replaced the other ones. Still want to get new tires for it and i don't want to blow all my money away.

The truck as:
new alternator
plugs, wires, cap, rotor
map sensor
fuel pressure regulator (fairly new)
fresh gas with some seafoam (help clean and stabalize the mixture)

Also, there is a tube coming from the oil fill neck on the valve cover going to the air cleaner box, what is the purpose of this? i removed the tiny air filter for it because it was bad and couldn't have been doing any good.

I will also be putting in a new fuel filter because that should probably be changed out.

Any help in straightening this problem out would be great and once agian, thank you to all that have helped in my previous posts.

 

The symptoms you described sound like a throttle position sensor. You can take the sensor off and check resistance throughout the range of movement of the sensor. If you don't get a steady increase or decrease in ohms, it's bad.

Greg B

 

could also be the idle air control. I just had mine out about an hour ago and sprayed it out with carb cleaner, couldn't even tell there was a spring in there, seems to be good now though. My truck would idle down when it was cold and stall out too. but not all the time, i'm still messing with it

 

Could be the TPS, could be the IAC.I would spray carbuerator cleaner in the idle air control valve before I tested it. I would hook a vacuum guage on it to see if you have 14 hg at idle and check the timing with the SPOUT connector off. Be advised if you change sensors it's a good idea to recheck the timing because some sensors can affect the timing. The TPS and IAC are good examples.

Some rules of thumb when using a vacuum guage:
*gauge reading steady 17-22 in Hg indicates normal engine in good condition.
*reading low (15-20 in Hg) but steady indicates late ignition or valve timing, low compression, stuck throttle valve, leaking carburetor or manifold gasket.
*gauge reading steady but dropping regularly indicates burnt valve or improper valve clearance.
*gauge reading dropping gradually at idle indicates choked muffler or obstruction in exhaust.
*gauge reading slowly dropping to zero as engine speeds up indicates choked muffler.
*gauge reading fluctuating between 15 and 20 in Hg at idle indicates stuck valve or ignition miss.
*gauge reading drifting indicates improper carburetor adjustment or minor intake leak at carburetor or manifold.
*gauge reading fluctuating as engine speed increases indicates weak valve springs, worn valve stem guides.
*gauge reading vibrating excessively at idle but steady as engine speeds up indicates worn valve guides.
*gauge reading vibrating excessively at all speeds indicates leaky cylinder head gasket.