Confusing stumbing no power misfire problem

Hey guys,
I've got a 1998 4x4 2.7l 180k Tacoma (no distributor) that I haven't been able to get running for a year. Last year it started loosing power and dying, no codes. Before i figured out it had burnt valves, I replaced the maf, IAC, spark plugs and wires, EGR, O2 sensors. After figured outoi had burnt valves (neglected to get valves shimmed) I swapped the head, did a good job on it, and it still wasn't running right, recently I got back to it and found that the cam sensor and maf (yes the one I replaced) tested bad. I replaced those and it was running pretty good, I test drove it and it was doing fine, but on idle it was a little shaky and started giving me the flashing misfire light. I read the codes and got, random misfire, as well as 2 and 4, and p0130 (O2 sensor) and p0133 (O2 sensor slow response) I replaced the O2 sensor and then full of hope test droved it, and it did good for a bit then totally craped out, and I had to drive it home backfiring and maxing out at 15mph. Now it has p0172, system too rich. I also tested the fuel pressure, and it seemed within spec, I don't know if the fuel pressure drops on accel or something, and replaced the regulator, filter and fuel injectors. Should have sold this truck as a mechanic special long ago but now I'm too deep. What the heck do you guys think is going on with it? Knock sensor? Crank sensor tested good. I don't think I have a vacuum leak. I've check, replaced some hoses. Also replaced the air filter and cleaned the throttle body.

 

Could be bad catalytic converters.

 

I only have 1 and I replaced it.

 

@mechanicjon @Bebop @gearcruncher might be able to give more insight.

 

Compression test? Leakdown? You losing coolant? Check your valve clearances? What brand o2 sensors you using? Toyota’s are picky at certain brands of O2 sensors

 

I did a compression test and all was good. I am not noticeably loosing coolant although I do get a pic of white after not starting it for a day, not sure if that's vapor or coolant, the white stops pretty quick. I am using Bosch O2s. Just had the shop rebuild the head I have not double checked their work.

 

Put Denso sensors in it for the O2s and MAF, Toyotas don't mix well with any other brand sensor

 

*puff of white

 

The exhaust pipe is really black and so are the spark plugs Mabey new plugs... Again?

 

Have not done leakdown test.

 

Toyotas are tested and built on the Denso sensor's exact specs, which is why you see a lot of threads on here from people that use Bosch sensors and run into problems. I would definitely look into swapping those Bosch sensors out.

 

Ok good to know I'll look into replacing those.

 

Check your egr system. Make sure the egr is closing all the way. What was the compression numbers?

 

April fools day guys!
OP joined today

 

Ok so here's the update. It turned out I had burnt valves. Replaced the head. Truck is better now, but still wacky. Now it getting up to speed great, and no more smoke, ect. The compression is good. So now when I am up to speed, the truck will intermittently, (every 2-3 minutes) start loosing power and if I floor it, it gets power back and I can pull back on the throttle. I will have to fight with the truck like this over and over for 2 - 3 minutes, after which it comes back to playing nice mode. This repeats. No problems under 50 mph. The tach and speedometer also flip out in unison then come back to working ever one in a while (every 30 minutes). What now?

is my fuel pump going out? Im at 180K.

I tested my cam and crank sensor, but I guess the problem is intermittent.

I bought one coil and changed it around to see if that would help (therer are two)

I have new fuel injectors and fuel pump regulator.

I have new maf

I have no codes

At one point I had a no start breakdown from corroded battery ground. I cleaned it but I didnt clean the other grounds. Some seem crusty.

I have Durlast plug wires with I think NGK plugs, and probably bosch O2 sensors still I think.

I dont know if I messed up my cat with all the previous misfires.

Just fixed all the exhaust leaks.

What do you guys think?

 

Oh lol I posted this after the new head. I forgot and went over it again...

 

Also I had 3/4 tank of 2 year old fuel in it. Topped it up with fresh and added gumout. Could it just be the bad gas?? I guess Ill find out.