If it is ticking over this low i would look at two things, first is the coolant temperature sender sender as these are prone on these vehicles. Upon failure it will put a default fixed setting into the ECU instead of the variable values of the working sender. This usually makes starting fine, just a little lumpier than usual when it is cold, but it will run reasonably well once warm.

Secondly look at the knock sensor, this advances/retards the ignition timing and adjusts the tick over speed as it reads from a different ECU map. You will need to be hooked up to a fault code reader to prove the knock sensor though.