driving to the dump today, my oil pressure gauge dropped all the way to the L, then bounced back up to normal. i kept an eye on it the rest of the way there, and it kept dropping to the L, then back to the normal, sometimes hanging at the L for a second or two.
when i got off the freeway, it kept doing the same thing, and i noticed my truck sounded almost exactly like a diesel.
checked the oil level and checked for any obvious issues under the hood, but everything looked OK, other than the noise and the wonky oil pressure.
drove perfectly fine yesterday, no signs of trouble.

the needle seemed to drop when i hit the gas, and return after a pause or after i let off the gas, but it also seemed better up and down hills.

here's everything that has changed recently:
new oil cap yesterday,
topped off oil yesterday, it read a quart low, i added a quart,
got gas at costco (regular 87)

oil and filter were changed about 500 miles ago with mobil 1 10w30, i did a seafoam treatment about 200 miles ago. it has a new fuel filter, cap, rotor, and coil, all within about 500 miles. also set the timing to 10*


i do know i have an exhaust leak and that leaks can sound all kinds of odd, but i cant see it changing that much overnight.

any help is appreciated, this is my daily driver, so i need to figure this out quick.