SO when I went to start my truck yesterday, it turned over and immediately revs up to 2500-3000Rpms and just sits there for about 30 seconds and then slowly, and I mean slowly, starts to drop. It does this on cold start ups and warm start ups.
I put a new TPS and IAC in it about a year ago, so I don't believe that's the problem. Any ideas?

 

clean the net on the maf sensor

 

Just cleaned both the throttle body and MAF about a month and a half ago, but I'll try it again. But now today, it is fine, so I will wait until it does it again.

 

Just had the same problem a month ago and after spending money on a new IAC, MASS air flow (tried cleaning them too), O2 sensors, spark plugs, and fuel filter, it turned out to be a ripped vacum line that runs along the head covers. But it also drove poorly and idled bad. So not sure if your truck runs fine when its warmed, or during operation. My truck also would come and go but eventually it gets really annoying, Hopefully this helps.
2003 Ford Ranger FX4 LVL II

 

First off, sweet truck Corey. So my truck does run like crap along with a little drop in fuel mileage. Did fixing the vac line help out with that then? I'm sure I can find it, but any pics would be cool.

 

With EFI, any vac leak can cause rough idle and possible high idle. For the 4.0 SOHC, it is fairly common to find a leak in the PCV elbow. Ford sells a rather expensive replacement assembly that includes the elbow but some owners improvise with off-the-shelf automotive hose instead.

 

^ I already did that when I bought it.

 

Hey, Well The picture above (Previous post) was the problem I found that was causing my hesitation and bog, that elbow in the vacum line was ripped. It was a gas hog for a little but once the vacumm line was fix it was fine. Have u replaced your fuel filter? Is the check engine light on?

 

Yeah, did the fuel filter twice, no CEL. It hasn't done it for three days now so maybe the little gremlin moved on to something else.