Jetta help

Hello, I'm having an issue with my 1998 Jetta GL. (stick, 86k miles) Whenever I'm at freeway speeds, and the accelerator is pressed, I hear a repetitive clicking noise. the faster i accelerate, the more repetitive it gets. (doesn't sound like metal grinding or anything like that) It's not particularly loud or too pronounced, but its annoying. I'm wondering if any of you have had this issue before or know of it, what the problem is, and around how much it would cost to repair? (Or if its something I can do myself)

Any information would be appreciated. Thank you!

May sound obvious but, Rock in the tire tread?

check your belt too your altanaiter an see if it is fraying, becuase it might be rubbing the faster an faster you go, i have seen it happen in the past with the 98 versions
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