My heater will ignite then stay on for about 1-3 minutes then shut off and cycle through the ignition cycle 2-3 more times sometimes longer and eventually stay on. I changed the limit switch and cleared the pressure switch tube of any condensation but it keeps doing ot.

Did you clean the burners and flame sensor? Any fault code on the control board while its doing this?

It is the flame sensor/milivolt generator/thermol couple. Which ever your unit has for flame sensing. Take it out clean it and retry or replace it.