misfires - tried almost everything I can. any help welcome

Hi All.
I am putting out a life line...
I need some insight from experienced members on what I should do next.
I have a 02 taco 4x4 v6 crewcab. 183K miles.
New engine put in 3 years ago. long block due to cracked head near #4 cydr. (from what I understand is common on these v6's).
After installation by local shop, ran okay...
After a little while leaks occurred and then the dreaded engine light.
never did find the leaking, over time they kind of went away...
but po300, po305, po306, code showed up on the code reader.
my first thought plugs, wires, and ing. coils.
I switched out coils with no change. plugs seemed fine, and got no where with that.
cleared the codes, ran it again engine light came on, with po300, po301, po303.
This was after i had switched coils back to original cydrs.
My only vehicle at the time so i had to drive it. After a front brake job (in-house tundra calipers upgrade),
for some reason it ran like a champ!...no power loss/hesitation, actually lots of power! ...i know!!!
Ran good for week and a half then the engine light and poor acceleration...
At this point took it to the dealer (because I was wondering about warranty on the new engine. maybe it was with in the new engine and Toyota dealership would figure it out.
They said it needed new wires. okay, $477 later I drove it away on a Friday. seemed okay for the day (20 miles of driving).
the very next day, 10 minute warm up and then a acceleration on the freeway, engine light and hesitation from engine.
Took it back on Monday to the dealership, "well we will look into it some more...but will cost you"
i was pissed, and declined.
drove it here and there...

took it home. changed out the fuel filter for new, new air filter, new Mass air sensor, new plugs, cleaned the throttle body, and yesterday I have po303, and.. 171, 174 (i think thats the two for lean mixture).
and do I really need to spend 3 bills on 3 new ing. coils!?!
Im a single dad of two, and cant afford not to feed my kids much longer! (jk) Im going broke on what I want to call trouble shooting "preventative maintenance".
Last thing I can think of is gas cap?!? ...before I turn it in to a shop for next step and another diagnosis/repair bill. Which is what, compression check,
and injectors (big bills right?).
Is there a computer malfunction?!
CAN ANYBODY GIVE A BROTHER SOME GOOD ADVISE AS TO WHAT TO DO NEXT!? Going on three years of nightmare headache!!

 

I'm inclined to think TPS, but I would be very interested to hear from the group on this.

 

@Jimmyh

 

Thanks Atty!

Since, ...I was just over it!
I took the truck into a reputable shop, and they uncovered a faulty ing. Coil. And a issue with a gasket on the throttle body.
Day two of completed repairs, and truck is running great.