Bad gas mileage and strange whirring noise even with serp belt off

Not sure what’s wrong with my truck. A couple things are wrong with it. No CEL. It gets horrible gas mileage. I think it’s around 10-11. Not sure but I know it’s not good. I have a 2011 Tacoma TRD Sport Auto with 126k on odometer. Typically I only drive it short distances like around town or to work (about 5-6 miles some on highway). On occasion I’ll take it for a 300 mile plus drive. I usually have to fill up after 230 miles.

At around 110k the tb was cleaned. Not sure if they did mafs but it’s right there so I’d hope so. Also had front diff fluid changed, t-case serviced, power steering and coolant flushed at same time. I can’t remember but I think the service guy said I had a slight exhaust leak. Not sure where.

Spark plugs were changed with iridium plugs (not sure what brand) at 88k. Same with k&n air filter (probably gonna take that out after lurking around here for a bit). Probably should replace these anyway with copper.

I had the tranny drain and filled/new filter at around 100k. Also replaced the rear diff fluid then. Since then I’ve noticed slight seeping from the tranny pan. Not sure if this would be contributing but wanted to add for full disclosure.

I do all my own oil changes every 10k using Amsoil 5-30 sig series with k&n filter.

As far as problems besides bad gas mileage I’ve been having a vibration problem mainly at highway speeds but even at 25-40. It’s intermittent but happens at various intensity whenever I’m driving. Usually, but not always, I’ll feel it on the same stretch of roads but the vibes aren’t always the same. I’ve checked all my Ujoints and nothings loose or appears to be binding (I’m too lazy to remove it completely to check it properly). My carrier bearing has slight hop but I’ve seen a lot worse. The rear slip yoke has slight up and down/side to side play though. I greased everything up but it didn’t really make a difference.

I also have a slight whine that can’t be heard while idling normally. Only when I rev the engine or when I’m driving. Unfortunately my loud exhaust makes it harder to hear things lol. The thing that sketches me out is I removed my serp belt and still hear it. Unfortunately i was by myself and didn’t have anyone to rev it for me to try and pinpoint where it was coming from. I hope to God it isn’t the oil pump or a bigger issue with tranny. A whizzing/whirring noise does seem to be present from bell housing at idle tho.

I was fearing the worst that it was internal damage because I could hear a random rattle (like a rock tumbler) from engine when idling. However, my ps pulley is bad bad and after replacing my belt (which after replacing made a horrible whine when turning wheels for about 2 mins) I could really hear that rattle when turning. It only rattled when turning too. Tensioner pulley is bad as well.

Not sure about what to do here. Any ideas? I was thinking about doing the ps pump and tensioner pulley myself (tension seems fine) but don’t really want to if I have a bigger issue. Is the Ps pump a PITA? My mechanical inclination only goes so far.

 

I did do the tap brake test with slight throttle to check torque converter. It may be that because the vibe isn’t as bad but I can still somewhat feel a vibe when doing it.