Gas and Oil Home Heating Furnaces - gas furnace pilot ?

our furnace fails to run sometimes. the "83" Magic Chef has been running ok untill recently. It has a spark type ignition but the pilot continues to burn after the furnace has cycled.
I've read some of the past postings but did not see one covering this.
I'm not sure if this is an electrical problem or a mechanical problem with the gas valve. Hope you could point me in the right direction.
BTW
it has a johnson contol G65bbg-1 ignition control. and it's a magic chef e96a75d-7 forced air gas furnace.

I'm going to out on a limb and guess that the pilot continuing to burn probably means that the furnace is NOT cycling off on the thermostat. If the thermostat were satisfied, the pilot would be shut off to await the next on cycle. What is more likely happening is the main burner is shutting off due to the ignition module not getting a strong enough flame sensing signal and the module is keeping the pilot lit and then trying to reopen the gas valve after a delay. Your furnace uses natural gas, correct? Is there also a Johnson Controls Y79 lockout module in the furnace? I kinda doubt it. Take a look at the posts again for some ideas on what to look for when the flame sensing circuit is malfunctioning. Look especially at one from this week under the name Mike Crawford.
To get you started, make sure all the ground connections in the furnace are clean/tight.

from big john. with the details given as vague as they are he may well be right on it. thanks big john for your insight and postings, time after time you hit it on the head!