All,

I have been trolling previous posts but haven't found any that applies to my specific case, as I have already checked the battery and other first basis checks.

When I am driving down the road, and I let off the gas, the truck feels likes it's about to die, stumbles around 450-600 RPM, and then begins to fluctuate around that area until I make it to a complete stop, then dies. If it's in Park, it turns over and acts/sounds like it starting, then dies. It shifts perfect through each gear, and still has 100% power in all gears, it's only when I come to a stop or put it in Park.

Now I have already run the OBD-II scanner, but it didn't pull any codes. All fluid levels are perfect, just recently (900 Miles ago) had the oil changed, no funny smells, sounds, or anything obvious.

My dad (old shadetree mechanic) believes it to be a bad vacuum line or bad gas, but he is unable to come take a look while I don't want to drive it as it is. The only thing recent that has been done that could have an adverse affect would be me cleaning and re-oiling the K&N Filter, but I took a complete 24 hours of cleaning and re-oiling before putting it in the truck.

If this is indeed a bad vacuum line, how would one go about checking this?

Would anyone have any other idea's on this one?

 

start by checking the battery and the IAC motor (kinda sounds to me like your battery is gone, when you are on the gas the alternator produces enough voltage to run everything fine, but when you let off it the voltage drops and battery will normally pick up the slack, if it doesnt, the pcm goes WTF?!?!?!?! and kills the truck)

 

Thanks Sharps.

I replaced the IAC about 15,000 miles ago along with the TPS, and the MAP sensor.

I had to jump in the Wife's Mustang and haul *** to work, but when I get back tonight, I'll check the battery again but the voltage reading in the gauge cluster never dropped while I was monitoring the stats, but at this point it seems to be the most plausible issue.

Thanks again!

 

Could be a bad PCM. Did you clean out the Throttle Body when you did all of the sensors? Did you reset the PCM after each sensor was replaced?

 

Yup, we cleaned out the TB when all the sensors were replaced. It's run like a top until this, and after looking further into it, it does seem to be the battery. This is a 5 year old Wal-Mart Battery, and the voltage on the cluster is just below the battery icon prior to starting the truck.

I'm scraping by financially as it is, but hopefully I'll be able to find a decent second-hand battery some time tomorrow and let you guys know how it turns out.

Thanks again!

 

doesnt walmart have a 7 year warranty on their batteries?

 

Well, at this point I believe I have checked everything.

The battery is good, as tested bu Auto Zone. I took the IAC, MAP, and TPS out last night to make sure they were still clean, all three still looked brand new when I replaced them a few months ago. I hear the Fuel Pump kick on when I turn the key to ON, the Distributor Rotor looks good from the last replacement 15,000 miles ago. It's got brand new plugs and wires when the top end was rebuilt, and still... no codes...

I'm at a loss. Fortunately my Wife is 8 months pregnant and can't fit in the Mustang, so I have a car to drive, and her Mom is staying here during the evening while I work.

I didn't want to, but I may be having it towed to the Shop on Friday.

 

just because the battery tested good doesnt mean anything it could have a bad cell put the battery from the mustang in to test

 

+100000000

battery can pass a load test and still not be good enough for these trucks

 

A Wal-mart battery is garbage, especially a 5 year old one.