Make sure mat_queue_mode is the to 2 NOT -2.

Your hard drive is waay to slow. For gaming a 1 million rpm HDD is recommended, try looking for something running at 1.5-2 million rpm for optimal performance.

im not on my comp at the moment and the question mark means i want sure of the exact number, i may be missing a few zeros. also i can say that im fairly certain that it is not my hdd
Edit: this is my hdd http://www.newegg.com/Product/Product.aspx?Item=N82E16822149407

A 3.5 inch disk spinning at 192000 rpm works out to be 1790 meter rads per second, or 4004 mph. Your hard drive would literally be running at Mach 5.

On a more serious note, have you checked to see if your gpu is entering 3-D mode while in tf2? Sometimes a graphics card can stay downclocked if it thinks that the load isn't high enough to warrant 3-D mode. Try this: https://forums.geforce.com/default/topic/487091/force-3d-clocks-stop-downclocking-on-windows-desktop/

it might be a heat problem, a friend of mine used to have something like this, his was a lot worse tho, but basically everytime he started GPU intensive software, out of nowhere his GPU would spike to 255 degrees Celsius after gaming for a while (which gave hi huge fps drops), after weeks and weeks looking for a solution he ended up buying a replacement, so I'd advise to monitor your temperature while one of those spikes occur to see if it is hardware related!

255°C!? And all it did was just give high fps drops??

255 thats pretty crazy. however i make sure that i have evga precision (oc and fan monitoring) on everytime i start my comp. i never go above 64c playing anything.

255 is the maximum value of an 8 bit integer. If any delicate electronics got that hot it would definitely damage it to the point where it wouldn't function anymore. It was probably a broken sensor and 'regular' overheating causing the downclocks.

so i tried all of your solutions, the mat_queue_mode 2, forcing the 3d clock. and none of it worked. i even started up a game of bf4 to make sure my fps was the same as it was before this started happening. it was.

steam overlay have this problem that it locks your fps at 60fps at random times. Might be your problem. Disable and check.

disable vsync, steam overlay and clean your processor

Why vsync?

I had this exact issue when I was playing off a laptop with an i7-2630 QM (I think that's the model)

Basically what would happen is my CPU would get to about 65-70c and downclock itself until it cooled down causing horrible fps drops.

If that is the issue you're having it would explain why you don't have this happen in BF4 which is a highly GPU dependent game, and it does happen in TF2 a highly CPU dependent game.

I don't know because i have a really bad hp laptop with a cooling stand made out of jenga blocks and i can easily get constant 60+ (100+ in spawns) fps with maxframes + stabbysfps. (i dont use no hats)

I really dont understand why people get constant fps drops, it might just be tf2 and the somewhat poor optimisation.

Also have you disabled steam cloud before reinstalling. You also dont need to reinstall the entire game just back up your maps/custom/demos, delete the tf folder and verify game cache. It takes less time.

There's also this:
http://teamfortress.tv/thread/7639/fps-improvement-compilation

To verify everyone saying that spike wasn't possible, it was a broken sensor(forgot to mention the spike wasn't the actual heat :P), And that made the GPU downclock hence the fps drops ;)

To shut everyone up about overheating issues, download HW Monitor, play Tf2 for at least 30 minutes, and check your temps. If anything is over 70c in the 'Max' column, post here.

When you said you reinstalled in the OP, was that tf2 or windows?
Can you post your launch options?

Some other things to try:
Update/reinstall graphics drivers
Try an older driver
Disable antivirus when running tf2
disabling hyper threading in your BIOS
In the nvidia control panel,under manage 3d settings, click restore
Alot of things to try here