I'm looking for suggestions on what I should check for this problem..

Here is what happened:
- I was at the beach last month, and decided to take my truck out on the thick sand.. It went like a tank last year, so I did not anticipate any problems this year.. Anyway, as I drove into the thick sand, the truck dug in some.. Pressing the gas pedal all the way to the floor would not make any of the tires spin.. I backed up some, and took a run at it again, and again the truck acted like it had no power, and would not go anywhere.. I ended up putting it in 4-wheel low, and slowly backed her out of the sand..

- I've also noticed a difference on the road.. She runs great on the highway when I punch it and the tranny shifts to a passing gear, but if I just give her moderate gas, she barely accelerates at all..

Any suggestions?? See my mods below.. Fuel filter dirty?? Spark plugs worn?? Need to clean MAF sensor??

Thanks!!

 

When did you add the FIPK? These get hot underhood air when going slow and can cause no power.

I thought about the catastrophic converter, but you say when you punch it on the highway it has lots of power. Usually a clogged converter causes the opposite problem. Same thing with a clogged fuel filter.

The MAF sensor might be clogged, sometimes if you put too much oil on the K&N it ends up on the MAF. This can be cleaned with alcohol.

 

I've had the FIPK for over a year now..

 

If you haven't done so, I would change your fuel filter. Ford actually recommends doing it every 15K, although I waited until 30K. Your going to need the fuel line disconnect tool to change it though. ~$9 at you local shop.
Jes

 

I was thinking the same. Was the ambient air temp much greater or more humid ?

I notice on ~ 85* nights driving, that the intake temp is about 106*F with the K&N. If it gets really hot ( ~ 100* ambient air temp ) and the humidity is up, the truck goes like crap until it gets air moving on it. ( like you said highway is fine ).

If you know the outside temp between the 2 times you went out ( and if you can recall overcast, and humidity ) then try to find a day like the first days you went out. Don't know if the weather has been that drastic around you, here is has been hot for the past 45 days, with few reprieves. I first noticed this on the friday before the 4th.

I always noticed on sunny days that the UV seems to warm the heck out of the sand.

Checking for a dirty MAFS is another good idea as well.

I would thing checking the temps of late versus the month ago might give some insight. It has nothing to do with when you put on the FIPK, but what the temps were when you were using it.

Another quick check is to put the stock intake back on, and check it on a day like the last one.

 

HI!... Check your CATS. Mine started out just like you were describing and slowly got worse and worse. Eventually I could'nt go over 2000RPM or my truck almost stalled. Took my CATS off and found out that my PRE-CAT on the driver's side fell apart internally and plugged up the secondary CAT behind it. I temperarily removed the CATS from both sides and got ALL my power back. I'm currently waiting for my FULL MAGNAFLOW exhaust system to get here so I can swap out the factory JUNK and go with the S/S MAGNAFLOW.