Few things to check......
Burner tube
*Tube needs to be free/clear of obstructions (blowing air doesn't remove spider webs.....bottle brush cleans tube)
*Needs to be aligned with gas valve so that propane flows directly down center of tube
*Spreader at end of tube needs to be centered/squared to end of tube
Spark Electrode
*1/8" gap between spark and ground rod
*Spark to ground rod only
*No cracks in ceramic
*High tension wire clean/tight connections
****Needs to be positioned directly in flame for proper ignition and flame proofing
LP Regulator
How do the stove top burners appear.......good steady flame with ALL burners on high. No decrease in flame size when lighting other burners?
Then reg probably OK.
IF flames diminish in size, change color or are not steady then LP Reg may need adjustment or replacement