Acceleration Hesitation

[Zuiun]

The Vehicle: 1999 Mountaineer V8 w/ approx 144,000 miles. Reasonably well maintained.

The problem: For the past couple of weeks (I don't drive that often, as I work from home), it has been hesitating upon acceleration from a stop -- but only only at the beginning of the drive. That is, it feels like it's hesitating through first gear, possibly a little in second... but once up to speed, there are no problems. And within about 5 minutes, the hesitation goes away completely. Sometimes it'll come back if I shut off the vehicle and come back (such as a grocery run), sometimes it won't.

Thoughts on where to start troubleshooting?

 

[Ionizer]

I had a similar issue happen with my 98 SOHC. I would intermittently get a hesitation with acceleration from a stop. Had the X die a couple of times in an intersection or coming of a freeway ramp.

From my readings here I was directed to the IAC valve. Very easy to get too and remove. $5 for a can of carb cleaner and your good to go. Make sure to clean the felt filters as well. I was amazed how dirty it was and could see how performance would be affected.

Before I cleaned the valve this hesitation would occur maybe half a dozen times every 10,000 miles. It's been over 10,000 miles since I cleaned it and have only had one very slight moment of hesitation with no stalls.

I read that the DPFE sensor can also cause similar issues and was considering changing they out as well for good measure as it's easy to access and only about $60.

 

[Zuiun]

Thanks for the tip. My investigations also lead me to believe that my MAF is either bad or headed that way fast. So I'm going to clean/replace that and clean the IAC valve.

Where is the DPFE sensor located on the 99 Mountaineer? I know roughly what the part should look like, but I can't for the life of me locate it.

 

[1998Exp]

The DPFE is mounted on the firewall, roughly behind the center of the intake manifold. Most of the original ones failed in their early life, so yours have probably been replaced. However, the DPFE is not a likely source of your problems, because a failure of the DPFE (or any other part of the EGR system) will set a code and turn the CEL on.
Assuming there are no codes and CEL is off, I would start with the basics. Cleaning the MAF can't hurt. How long since your ignition wires were replaced? Except for the newer silicone ones, they weren't good for more than 50,000.