I recently had a problem with the thermocouple not allowing the pilot to stay on. That's fixed. Now.. the furnace takes a long time to heat up... approx. 4-5 minutes before the fan will even turn on and the air blowing out doesn't feel very warm. The furnace ran for 45 minutes and did not heat the room temperature to 68 degrees. Do I have a gas pressure probem? What should I check? The flames across the burner look even but may not be big or hot enough?

Well first make sure the burners and orfices are cleaned, a partially blocked orfice could block the proper amount of gas from reaching the burners. If all is well there, check gas pressure, for this you will need a special device to read gas pressure.