rlcole321

If it is just a spun bearing, then you don't need another engine, at the most, new or reground crank, maybe a connecting rod, and parts, much cheaper than $9K. sounds like they are not being honest with you!

It might be an alinement or suspension issue, hard excel. lifts some of the weight off the front tires and it may be a wheel shimmy, just a thought. (also make sure it is in 2 WD)

I live at the beach, so I just use Ospho (phosphoric acid) to spray the under carriage. just don't get it on the paint. It comes in different strengths so get a fairly med. strength, Paint and body suppliers carry it. It converts the iron oxide to iron phosphate. It's even paintable. But you do have a lot of rust, so it may take a lot.

I second it!, check header bolts and gasket. Did you keep the AFM system?, did you re-tune after top end replacement?

You could try a "reset", clear memory by disconnecting the batt. over night then drive it around till operating temp., then try to duplicate. Also, with a tuner possibly you could change the "Tip in" timing curve, to help that, but of course not sure if a small change is able with say a HP Tuner. I have an 18 Rado L83, but I choose to run 93 cause Buc-ees station here has CHEAP 93, 40 to 60 cents cheaper than anybody else.

The LS engine is a good motor but with one "week" spot, the AFM system (turns of 4 cyl. under cruise condition), but unfortunately those lifters (which collapse by design to turn off the cylinders) fail and thats what happens. Sounds like thats a "Dealership" price, if you not able to repair yourself, I'm sure there are better (and cheaper) places to get it repaired, even installing a "Non AFM' cam and lifter kit and mod the software to tune it out.

Seafoam makes a good product for that, it has a special tube that can be routed under the intake tube where you can start the vehicle and clean the whole intake system Sea Foam SS14 Cleaner and Lube - Walmart.com

Sorry for the issues you are having, but you shouldn't place them all in the bucket "they are bad vehicles". Design and workmanship are two different sides of the coin, I personally have never had any issue with any GM I've own with info screens, but most "issues" with electronics can mostly be traced to workmanship, poor connector assembly, bad or poor ground connection, or just damaged devises from weather, shipping or assembly. Ground connection are the most common issue since they are all over (and hidden most of the time) the vehicle. Normally a good technician (with the right info) can trace and fix those issues................just my 2 cents worth!

Yeah with the recommended oil 0W20, that's fairly normal in hot weather, cruising speed should be about 40 psi at operating temp.

try putting the jack stands under the rear axle and putting it in gear to see if something is out-of-"round"

Some aftermarket scanners will only read engine codes, is this the case?

try putting the rear axle on jack stands (loading the axle) and put in gear and watch to see if you can see something.

Keep the post going for info reasons, thanks.

3 hours min on batt disconnect to clear memory, why doesn't the AC work?, a faulty AC high pressure switch could be the cause, "fooling" the VCM into high Freon pressure, turning on fans and disabling the compressor.

I would definitely like to hear the end of this scenario!!

Minimum 3 hours on the batt. disconnect to clear.

Just curious, when you say "It turns over but not enough to start", saying it barely spins over (which would indicate a Batt. problem), or it is the normal cranking speed, but it just will not "fire" up to start?

"The rpms climb up high but the speedometer doesn’t move very fast. It’s like something is holding it back" if the engine rev's but slow at moving, sounds like the torque converter is "Slipping"

The Batt needs to be disconnected for a min. of 3 hours to clear memory.

Sound's like a sensor problem, may have to purchase a detailed schematic of the auto-air system to see how many sensors there are and locate them and test them individually.

Because of the thin air.

I had a similar problem with a car I had, it was a flat lander car and when I visited the rocky mountains and got up over 6K ft., the normal dual fan operation would no longer cool the rad., and by the time the "Second" fan was commanded, it was to late, overheating took place. I had the "Jumper the relay" on the second fan to keep it running all the time, then I could go all the way to 12K ft. Another "interesting" event I noticed, sometimes the incline was so steep, I had to keep it in low gear, and some times,(fuel injected car) I would notice that my accel. pedal was on the floor sometimes creeping up at 25 mph. when above 10K ft. (Rocky Mountain National Park)

about 10 seconds between cycles.

First thing to try is to clear memory, disconnect the batt. for at least 3 hours (overnight works too), and then try again, if it comes back right away then check fuel system, pressure, possible water in the fuel.

If it is "out of warrantee", then it sounds like a ground problem some where, or a failed controller. has any performance parts been added?