would anyone know in which line of the aircraft.cfg I need to change to decrease the response time of the aircraft engine? example; I give full power and about 2 seconds later the engine accelerates, this problem is only with an aircraft. Thankful!

What type of aircraft?  Jet or Prop or turboprop?  In jet aircraft it's pretty normal.  It's called spool up.  I doubt if there is any adjustment in the aircraft.cfg.

"Unlike general-aviation aircraft, every bank, pitch and power change in a jet airliner takes a few seconds to show results on its instruments. Impatience worsens the problem, so jetliner pilots get accustomed to the way their aircraft handle and give them the extra time they need for responding to controls."

The above is from Bill Stacks Jet Simming digital book. In a lesser way this also applies to less massive biz jets and turbo props.

This is normal behavior and very important when landing to realize it takes a few seconds for throttle input to kick in never be too slow and low in a big jet on approach close to the ground there is no instant response with the mass of a large jet.