"I haver a forced hot air system. There are 4 burners . The first two in sequence light and the 2nd two do not. I have the burners out. They all look the same. All very clean. What do you suggest I do.

What is the Furnace brand and model and do you know if it is a 2 stage burner system? If it is, it might be working correctly. Only 2 burners come on depending on the computer and when more heat is called for, the other 2 come on. If you are happy with the performance, it's probably working OK.

Check the gas pressure. Make sure the burner orifice is not restricted.