How can I fix my 4 year old Goodman GMS81155CNA heater?

I have a 4 year old Goodman heater model GMS81155CNA that we just replaced the blower motor on, fortunately it was under warranty until April. Now it keeps trying to cycle 2 or 3 times before the burners actually go on, sometimes it will ignite on the first attempt other times it won't. Often we will have to flip the emergency burner switch to get it running again because the temp will drop in the house and it won't kick on at all. The repairman said it's common of the Goodman's since the glow stick is not mounted in the proper place and is a bit misaligned. Another repairman, over the phone, said it sounded like a pressure switch problem. The heater will also go on for short periods of time and shut off. It will reach the desired temp and when set at, let's say 75, will continuously run until it reaches that temp so I don't think it's the thermostat. Any thoughts or suggestions I can give my handy husband to try would be much appreciated.