After a 180 mile trip over the weekend, I noticed my Trackers idle was hanging, around 1100 to 1300rpm. As of today, Ive tried: Pinching every vacuum hose coming off of the TB and intake, no change. Removed cover for thermal IAC and the wax pellet is firmly pressed out.  Removed ICS and tried cleaning it (Wasnt very dirty). No change. I had a timing light hooked up so I can view RPM from engine bay, and backed out idle adjuster screw. To the point it wasn't even touching the throttle shaft anymore. So butterfly fully closed and idle wouldn't come down past 950. (Took photo for reference for where to put screw back).  Also sprayed WD40 around TB, 2 times. No changes, the idle wont drop. I've run out of ideas. Anything else I should check or test? Note, Tracker is a manual. Other then the idle, it runs fine. Passes Calif smog. On my trip I was getting 26 mpg. No engine light. Thanks in advance.

You have air entering at some point after the throttle plate, we can tell this because the engine continues to run with the throttle plate fully closed - the customary method of diagnosis is to pinch the hoses one by one, until you find the culprit, but, that assumes the air is entering via a hose (or a single hose), what if it's not through a hose?  what if it's through more than one hose?

I've no personal experience with the 8v TBI engines as we never got those in my neck of the woods, so I can't provide specific guidance - a smoke machine is one approach (there are DIY plans on the internet that use a soldering iron to heat mineral oil until it smokes), you introduce the smoke into the intake and look to see where it escapes.

Was the PCV line one of the hoses you pinched, I've had a similar situation to the one you describe on a different Suzuki, and it turned out that the PCV valve had come apart shedding it's internals into the cam cover and allowing more air than normal to flow into the intake.