ok i have a 93 f150 the above stated engine seems to have a vacum leak. iii have had a lot of help from this site since i bought this truck so hopefully someone can help me figure this out.
what i have done to the truck so far
plugs wires cap and rotor
iac motor
upper intake gasket all new vacum lines
blocked off egr
disabled air pump and capped all lines
new pcv valve
seafoamed in intake and gas
new [to me] computer
new map sensor

now the truck runs alot better and get very good milege about 20-21 on the highway and 16-17 in town. but it has a horrible hesitation when cold and slight hesition when warm. can hear what sounds like a vacum leak but cannot figure out where it is coming from, i went to town on it with a can of carb cleaner trying to pin point it but have turned up nothing. when its cold i have to hold the gas down to keep it from dying for about 3 mins. i installed a tach and when its cold it idles about 700 and warm about 1000. i decided to hook it up to the scanner and every thing seems normal air charge, temp coolant, tps, o2 sensor, etc the only thing i cant figure out is when start it cold with the iac plugged in it idles at 2000- 2200 for about 5 seconds on the scanner the iac is showing 99% when it does this and then drops back down to 49%. i tried with both computer and the same result. so right now i leave the iac unpluged because i really dont like a 2000rpm cold start. but even with it plugged in i still have to hold the pedal to keep it dlng when cold just not as long. checed fuel pressure and t was 45 koeo and 53 koer. oh and when i did the cap and rotor i did set the timing 10*btdc. this has turned into a real head scratcher for me if anyone has run iinto thiis or can give me some insight it would be much appreciated thanks.

oh almost forgot no codes present at this time.

 

anybody have any ideas

 

Yes.

Disconnect the battery negative cable at the battery.
Then unbolt the ground cable that goes from the battery negative to the starter. Wirebrush the cable connecector at the starter, the area on the starter where the connector is seated, and wirebrush the ground point on the frame where the negative cable bolts via that "little bent over connector" is as well as the area on that "little bent over connector" that contacts the frame.

I did this on my truck and it worked wonders.

Give it a try.

Bob

 

Something else.........

I had a vacuum leak that I could hear.
Turned out to be a vacuum cap on the PCV valve had fallen off.

Just a place to look that's a bit hidden.

Bob

 

vacum cap like the pcv is a t or has more then one outlet?? i will be trying the ground cleaning today and will let yall now what happens

 

My "new replacement" PCV valve had two vacuum ports on it.
My truck only required using one of those ports.
Inside the package (when I purchased it) was a hard plastic vacuum cap that I used to block off the unused port on the valve.

That "hard plastic cap" somewhere, somehow fell off and did cause a vacuum leak I could hear, most noticably around the right rear side of the throttlebody.
Of course that area is REALLY close to the back of the valve cover where the PCV valve is.

Worth a check.

Bob

 

ok well i cleaned my grounds and that did help smooth the engine idle out but it still has the hesitation i checked the pcv and it looked fine was not leaking cracked ect. oh and i have put a new tps on to with no help im at a loss. the truck runs great other then this problem

it seems like a lean condition to me. but i dont know where its coming from.