Hey I was hoping for some suggestions so I can save myself the money of calling a mechanic especially if it's something I can fix for considerably less. I am handy, just not great with diagnostics.

anyway it's a 2007 f150, 6 cyl long bed automatic transmission. the problem sort of came out of nowhere maybe a month ago. what is happening is when i brake hard, reducing my speed too quick, it sounds like it wants to stall (however it has NOT stalled yet). sometimes it does it even when i dont brake hard. it does seem to have something to do with reducing my speed, especially when i reduce it too fast by braking. I'm hoping it doesnt have to do with the transmission.. any ideas?

Do a tune up man, plugs air filter, fuel filter if possible

Run any codes get them checked

My auto car does this same thing when the tranny shifts from second to first when im on the breaks, buts common as hell in my case so i dont worry, it just does it. ( drops to 500 lowest maybbe 400 once in awhile ) how far exactly does urs drop?

This post was edited by IB0T on Mar 14 2014 11:41am

Could be a vacuum issue.

Most likely this im thinking

Try manually dropping to a lower gear to slow down to see if it acts the same. As has been said, it is most likely a vacuum or Air flow issue. The engine in your truck is known for developing leaks around the intake plenum grommets, but will generally throw a p0171/174 lean code when this happens, and it generally goes away when the car is warm. If you have any sort of OBD2 tool (think the $50 kind you can get anywhere) you can hook it up and watch the PIDs. You would look for Short Term Fuel Trim Bank 1/Bank 2, commonly displayed as STFT1/STFT2. If you have a vacuum leak this value will be positive, +10%-+25%. If that is the case you would grab a can of carb cleaner and spray around the plenum while watching the STFT. When the numbers drop, you found your leak.

Failing that, the first thing I would do (because it is cheap) is replace the air filter if needed and pick up a can of Mass Air Flow cleaner and c lean your mass air flow sensor.

I have a new issue, the engine feels like it's misfiring or hiccuping when i accelerate and particularly around 50-55 mph it happens more frequently almost consistently. I took it to the shop today and they couldn't find anything wrong with it when they plugged in their computer to see if it was giving any codes. They drove it and noticed the problem and suspected it could be an issue with the transmission and that I should take it to a place that works with transmissions. What do you guys think is goin on based off just that info? Just want to know what to expect when i take it to a transmission shop.. also concerned this may cost me a lot of money..

I wonder if an ignition coil could be going.

This post was edited by said_aouita on Apr 8 2014 04:32pm

Look in your intake to see if you have carbon build up.

Does it do it when you accelerate or at 50-55 mph?

it happens when i accelerate somewhat but mostly when im accelerating from about 45 to about 55. It really sounds/feels awful and worries me when it happens.