All right hear is my problem. I just got done changing the coolant and upper and lower rad hoses. I went to start it up after I was done and it idled realy low. I just thought it was the truck just circulating the antifreeze threw the truck but it never went away. I have to keep my foot on the gas or else the truck will die. When I start it up in the morning arould 40 F in the morning it will go up to around 1000 rpm and just go back down and die. I have to hold my foot on the gas till it get temp in it so it will want to try and run. Once it is up to full temp and I start driving around and come to a complete stop, it will act fine and sometimes it will be fine for a couple of seconds then start to run ruff the rpm will drop then die. When it is parked and the idle drops and trys to save it self and the rpm will jump between 300 and 700 rpm. So far I have replaced the Idle Air Contro Valve and it did nothing. The only thing that I have noticed it their is a very loud hissing noise comeing from one of the vac line under the hood. Im prety sure it is the lower one right before the throtle body that goes to the IACV, because when ever I move it the hissing gets louder and the truck will idle up. The other thing I tired was unpluging the TPS to see if it would have made a difference and the truck ran the same other then it thew and code that I unpluged it, I dont know if upluging it would make the truck run bad. The only other code it threw was a P1000 which I could not tell what it ment.
I hope someone knows what it wrong with this truck before I have to start throwing parts at it. I just spent close to $700 for replacing front end parts so I do not have a whole lot of money at this point. Any help would be appreatied thanks. And yes I did use the search button but all I found was replace the IACV. By the way my truck is a 5.4 with 108,000 miles on it

Thanks

 

replace your hissing vacuum line, should be less than $5

 

My thaughts too, chase the vacuum leak, these bitches like all the things runnin just right or she'll get pissed off. Like when take the PCV hose off and stick your finger over the valve. Something needing air aint getting it so that ought to fix things.

 

vacuum leak...

 

All right well I replaced the one that was making noise. But now another one is f*%$ing leaking and it still runs like chit but it does run slightly better. It also threw two new codes im not realy sure if they are related or not. P0171 which told me its to lean but I just cleand my AF1 air filter and used KnN oil which im not sure I should do or not. Also P1000 which says monitor not showing, I still dont know what that perticular code means. Tomarrow I am going to order every single vacum line uder the hood and hopefully this will end my suffering. Thanks for all the help guys.

 

P1000 means you have not completed a drive cycle since clearing the PCM. For the P0171, try cleaning your MAF with CRC MAF cleaner. The oil off your air filter may have gotten on the MAF.

 

Check your PCV valve. I was changing spark plugs and i popped that baby off and my truck did the same thing that yours is doing. I popped it back on and it went back to normal.

 

I replaced the one vacum line that goes form the TB back to the IACV and the one that is on the pasanger side valce cover and the little valve thingy that sits in the valve cover itself. So far it has gotten a little be better. I wants to idle a little bit more but when I start it in the morning cold it the RPM goes up then right back down. It does not stay up around 1000rpm like usual. Now there is still a sucking noise and I found out that it is coming form what I guess is a little brether on the back of the IACV so is this telling me that it is bad. I still have yet to replace the other vacum line that is in front of the TB. But it is so small I dont think the pipe is crushed and I could not quit tell what was still in the valve cover. So all I have left to replace is the little rubber that is off the TB.
So do you guys still think this is a vacum leak and I still should try to chase this down. Or do you think it might be something else. Any advice would help and thanks for the previous help.

 

Follow Torkum's advice. Those K&N filters are notorious for contaminating the MAF with oil. When applying oil to the air filter use only a minimal amount. Clean MAF with an electronic cleaner or one of the cleaners made for mass air meters. The MAF can cause all kinds of problems if they get contaminated. Good luck

 

Sounds like you have a vacuum leak still. Clean the MAF, since it's easy. I ran a K&N for 11 years on my '97 without ever having any problems........

 

All right I will go get a bottle of MAF sensor cleaner and hopefully help the problem. Thanks for the advice.

 

PO171 Turned out to be an 02 sensor on my truck....

 

Well cleaning the MAF with the cleaner helped alot. It does not want to die as easley when trying to park it. But the idle does not what to stay up with I start it up cold. I am going to replace the IACV which is still sucking in air and hopefully will fix the problem compleatly. Thanks for the help guys.

 

Well call me stupid. The problem was I pushed the damn intake tube of the AF1 in when I was changing the rad tubes and that caused it to run like chit. I feal like such a dumb ***.