They’re much easier than the vw to fix. Plan on buying some rocker arms as well as the valves. Many times they’ll break a few of them at the pin for the roller. Timing is a breeze and most of the time the balance shaft chains and their hardware is ok. Dorman sells a repair bolt for the upper position of the front guide that’s a worthy upgrade. Gasket/bolts is cheapest at gm dealer for us shops compared to buying at local stores.
Have you checked A/C ripple? A bad diode allowing a/c voltage into system wreaks havoc with a/c current type sensors, crank, cam etc. used to be common on many Chryslers to have the gauges going wild due to alternator.
Yes most likely of the level is full.
Actuator failures are somewhat common for that year range of Lexus/Toyota vehicles, enough so that even dorman is making replacements for many of them. It’s not a totally difficult replacement, door panel and latch bolts a few rods which have clips.
Regular 2.4? Timing chain should run around 500 for the ecotec. Variable cam Timing solenoids are also common failure point in these engines and are easily replaced. If chains are loose and jump it will bend valves/break rocker arms which requires cyl head removal to replace valves etc. most shops at that point want to replace engine at that point although it’s a needless exercise to replace when the head can be easily repaired.
Those fail weekly, we do minimum one a month at my shop on the full-size gm trucks and suvs.