Cylinder 1 misfire

History truck has 259k no issues in my ownership and was owned and maintained by a mechanic at Toyota dealership prior to me. 7months ago cylinder 3 misfired and I was loosing power badly. I Replaced the coil and it went away about 6 months later cylinder 4 misfires. then a week later cylinder 2 misfires not as bad and only on ignition or high rpm’s. I decided to Replaced all the plugs and added 3 new coils.
Currently have all new NGK plugs and all new NGK coils Cylinder 1 is misfiring. I have also run 2 tanks through with STP fuel injector cleaner mixed in and it hasn’t helped. Today I’m going to move the coil and see if it’s faulty but I doubt a NGK coil with less that 1k miles on it would go bad.( I’ll update this post after testing) Any ideas on what I should check next? Injectors? Valve gasket? What do y’all think?

 

You need to swap coils take one from a cylinder that is working fine and put it in the number one piston with the misfire and see if it moves

 

That’s the test I’m going to do. Update y’all soon

 

For now the misfire on Cylinder one is gone. I also added some sea foam to help clean everything out. Now when I’m driving the engine get up to high RPM 4-6 with little acceleration until I let off and let the RPMs settle. Only happens in 2nd and 3rd gear. Slipping transmission?

 

Denso is OE coil

I’m not saying you have a bad coil.
But it also wouldn’t surprise me either.
Swap coils and see.

But it seems you have a history with misfires.