1999ford 150

1999 ford 150 makes a fluttering spun when I accerarate

You will need to be a lot more descriptive for us to be able to help you. F150 or E150? Mileage? Engine size? Transmission? Maintenance up to date? Recent repairs? And provide a better description of the noise, when it occurs, what it sounds like, where it seems to be coming from, and how long it’s been doing this. Nobody can even take a guess based on your post.

I am a lady so I have trouble knowing all of these things but I have searched and found that the truck is F150. The mileage 176,000. Engine size is 4.6 liter. Transmission is 4 wheel drive. Maintenace as far as oil change is currently up to date.
The noise started a couple of days ago, I hear it when I accerarate, and the sound is coming from under the hood. I do not hear the sound when it is just idling. Thanks for your help