'99 F23A1 with 240000 starts quickly with RPM steady. The past few weeks at startup the RPM drops for a second and returns to steady. On the road for the first 1-3 minutes the engine loses power/hesitates. There are no codes and engine does not stall. The loss of power occurs with the engine hot or cold. Like clockwork, engine begins to run normal after just a minute or two? Any help is appreciated.