Toyota Repair: Stalling, hesitation, starting problem, air control valve, coolant temp

Question
Hi Ted,
We have a 93 Camry 4 cylinder, automatic trans with 205,000 miles.  Recently, it has developed intermittent problems such as completely stalling when coasting at speeds below 20mph(it starts right up again when turning the key), sometimes at speeds below 45 with no acceleration(basically coasting) when you first hit the accelerator, the rpm actually drops as much as 500 before gaining rpm.  Sometimes this is a lesser hesitation.  On two occasions after the car had been driven and then shut off for a while(not completely cooled) the engine would turn over fine with what sounded like one cylinder started to hit one time, but then no apparent additional firing on any of the four. A few minutes later, it would start right up.  Otherwise, when it runs (which has been the majority of the time), it runs fine.  The distributor, spark plugs, and spark plug wires were replaced 6 months ago(prior to these problems) and the fuel filter was replaced 3 days ago.  The intermittent problems have just started about two weeks ago.  They do seem to be increasing in number with time.  There are no codes that come up when jumping TE1 and E1.  I've done some checking with an ohmmeter on the coolant temp sensor and the air intake sensor following instructions in the Haynes manual without finding issues, but I don't have all the gauges etc to test some of the other sensors.  Over several years there has sometimes been a clicking (like a relay) that sounds as if it comes from the passenger side dash, but it has never affected engine operation and tends to be temporary.  I have tried to pinpoint the source of the clicking but without success yet.  I would appreciate any guidance or recommendations you could offer.  Are there more likely causes that I could pursue?  Thank you very much for your willingness to help!!!! I look forward to hearing from you.

Duane

Answer
It sounds like it may be a problem with the idle air control valve, these are known to stick and cause stalling and idle problems, it's located on the bottom of the throttle body, remove the throttle body and then the IAC vlave from it, clean the moveable valve using a carbon dissolving spray and a brush, do the same for the inside of the throttle body, re assemble everything and give it a try.