Gas furnace flame wont stay on in the night/early morning

had this issue for several years and several techs came out but no fixes. Most of time happens during the mid-night and early morning, and works properly in the daytime so the techs could not see any issue. Here is the description: " Normally happens in cold temp (below 30) and mid-night/early morning, working normally most of time during the daytime. The burner cannot stay on and results short cycling, the unit could stop before reaching the set temperature. . Inducer motor turns on ; 2. igniters ignite for approx 5 secs 3. Gas shuts off, 3. Inducer motor continues to run, while flame kicks on/off frequently, and the blower could starts after dozens of trials, and the burner could repeat on/off during the cycle. I took some advice from a professional and vacuumed the drain tubes (which goes to the trap) from the inducer, it worked for 2 months and seems failed again., Occasionally i noticed there is some water traces right underneath the inducer. The unit is located at attic, it is Goodman brand about 14-15 yrs old, had inducer, gas valve replaced last year, and I have cleaned the flame sensor but no improvement. Any comments or suggestions? Thank you