misfire at 5000 RPMs

I just had the head gaskets replaced by a local mechanic to solve a misfire. The heads were surfaced by a machine shop they checked the valves were all in good shape. It now will not rev past 5000 RPMs. I took it back to him and he doesn't know what to do because it is not throwing any codes. It is reproducible every time even under no load.

Timing belt and water pump replaced at same time, 235,000 miles, new coils, plugs and wires.

 

Often an engine that won't rev out is because of a clogged Cat, bad fuel pump or bad fuel regulator.

Those might not throw codes.

Are all your parts that you replaced TOYOTA parts? Used TOYOTA coils are way better than new cheap Autozone Chinesium ones. But I would think that a bad coil would throw a code.

 

I will check those out. It does have a new aftermarket cat because someone stole my original. I purchased new Denso coils because it had cheap ones on there, and new NGK blue wires, everything else came from Toyota.

I will check into the fuel pump and regulator, but it didn't have this problem before the work was done. Throttle response is improved and better fuel economy now.

 

Bad TPS? If the ECU can't figure out how far the gas pedal is pressed, it could not rev out.

Wrong firing order? Should not be it and it should run rough, but you never know. Easy enough to check the basics.