Ford Ka does not accelerate

I think they removed the cylinder head of this car to replace the head gasket. It seemed fine after that work, but shortly after, the engine started shaking at idle and the acceleration felt like it was sucking in power at times. Then, after a while, it would only accelerate up to 2,500 RPM. After that, it wouldn't accelerate any further, only up to 1,500 RPM.
I removed the air filter to see if it was due to an air restriction, but it was the same. It sounded like a truck when Jacobs brakes are applied, to give you an idea of ​​the sound.
Any ideas what it could be?

Czech that the multiple of admission does not have air leaks or that the butt packing is blown up if it is sounding like truck brakes, check the flow hose that is not cut or loose after the flow.