why after 20 miles the engine no responding ?

Having power from your engine is dependent on having the following elements in play -- 1 -- ample fuel pressure 2 -- ample ignition spark at the right times in the right cylinders 3 - proper ignition timing 4 - sufficient, consistent compression in the cylinders of the engine 5 - air flow unrestricted coming into the engine 6 - exhaust flow unrestricted The "engine not responding" could also be an automatic transmission concern, if it is not operating properly also. Testing is needed hands on with a diagnostic tool capable of monitoring performance data to find out what is wrong.