Toyota Repair: 1991 corolla 4x4, intake hoses, corolla wagon

Question
Hi Ted,
I have a 1991 corolla wagon (4x4) that has developed a severe idle problem.   When the engine is running the idle revs up and then reverts back to normal. This happens continuously but is worse when the engine is hot. When I remove the wires to the vaccum sensor the idle remains high and when I disconnect the tube coming from the vaccum sensor the idle drops really low and the engine runs really rough but is still driveable.  I took it into ultratune but I don't think they had a clue.  They turned the idle down as far as it would go, gave a few things a clean up but didn't fix anything (a big waste of money).  They suggested the thermostat was stuck open and there was a problem with my cooling system system leading to a problem with the auto-choke.  I change the thermostat and gave the cooling system a top notch flush all to no avail.  Anyway, if you could shed some light or offer a few possiblilities that would be awesome.  Thanks Billy

Answer
Does the check engine light ever come on? Is it on at this time? If the check engine light does not turn on while driving check for a vacuum or air intake leak, check the large intake hoses from the air filter, they have a tendency to crack, check all other vacuum hoses, especially the alrger ones for any that may be cracked or have become disconnected.