It rattles and it's very sluggish, as if something was missing. I changed the oil filter, spark plugs, cleaned the throttle body and it's still the same. The spark plugs I used are normal cheap ones, not platinum, and I calibrated them to 0.52, now it starts quickly, before it took a while. What can I do so it recovers acceleration and feels quick again?
You have to check the gas pressure in the fuel rail, this is very delicate and with a few pounds everything is already off. I had that problem with a King Ranch that didn't go over 70, I changed the fuel pump and that was it.