low idle at stops or when slowing down

[Connie]

Hi everyone,
I have a 1996 Ford Ranger I replaced the engine approximately 8 mos. ago new plugs wires timing belt etc.
I have not had a check engine light come on but the truck started revving at high rpm and then switch to a low idle as if it were about to stall out.
I changed the IAC today and noticed that the high rpm problem has not returned however i still have the low idle at stops or slowdowns (it has not stalled yet) I do smell an exhaust but I have had that every since i purchased the truck in 2004.
I have seen the threads for cleaning the MAF and i wondered if this would correct the issue. I have not tried replacing the fuel filter I am on a limited budget and do not want to keep paying someone to throw parts on it and every mechanic i spoke with is sure something else is wrong with it without plugging it up for a code. Would my best bet be to next replace the O2 sensor or clean/replace the MAF or see if i can find a mechanic who will just check for a vacuum leak without telling me i need a fortune in parts 1st?
I appreciate any advise I am Lost but trying.
Connie

 

[kimcrwbr1]

Hi if you clean the MAF you can use rubbing alcohol or maf cleaner no harsh solvents you can also clean the throttle body around the butterfly. You can take it to the part store and have them pull the codes for free and usually a vacuum leak will give you a high erratic idle. Did you reset the computer after you clean the TB and MAF or during disconnect the battery for 1/2 an hour then run it for 1/2 an hour at medium speeds cycleing the a/c if you have it and drive it to the part store if you still have the low idle. If it is running good dont do anything any codes set will clear themselves. If you change or clean a sensor you need to reset the computer by disconnecting the battery for 1/2 an hour. hope this helps you.

 

[kimcrwbr1]

Did you put a new PCV valve when you changed the plugs. Do it every time you change the plugs as a habit they are cheap and cause weird problems. The book says if it rattles it`s ok I dont buy that they cant be cleaned and they do wear out.

 

[Connie]

Thank you,
I had a shop put the engine in and he assured just about everything under the hood was new however it was a (used) engine and my odometer quit working a few days ago when this started. The only thing i have done so far is new IAC I will clean the MAF and see if that fixes the low idle where it feels as if it will stall out. I appreciate the help and I can clean the MAF without costing anything so i will definitely try that 1st and then go from there.
Connie

 

[kimcrwbr1]

Also check/clean around the butterfly on the throttle body too. Be sure and reset the computer just disconnect the neg on the battery while your doing that. Then run it for a bit to set the new values.