GE XL44 heating issue

Question

You helped me with some ideas which I implemented. Both ignitors work, so I changed the sensor. I noticed with the deflector pan off the bottom that the flame starts high and after a while drops quite a bit lower even before the temperature is near what is programmed. I.E. temp set to 350 and at 175 flames goes low making the heating process very slow to reach 350. Is there some gas pressure regulator or something like that that might be the issue?