Pings when hot 3500rpm

run the fault codes
indicates a problem in the torque converter clutch servo/solenoid
Take it to an accredited service center or professional auto transmission shop for a proper diagnosis
I would think that it is not mechanical but electronic control or low oil level

engine pinging( detonation) under load is from air /fuel mixture incorrect or ignition timing incorrect or a combination of both
most probably mixture is too lean ( detonation is spontaneous combustion like a diesel action) so any hot spots will ignite a lean mixture prematurely
places to check are the inlet manifold gaskets , carby mount and gaskets , float level , fuel supply, vacuum hose leaks and finally the initial ignition timing setting
most engines run at around 10 degrees btdc and the electronic module adjusts from there according to rpm
what ever you find . it has to be fixed as continual running in this condition will melt the top of the pistons

The engine may misfire and/or buck while driving at freeway speeds with no fault code stored in the powertrain control module (PCM). This can be caused by an intermittent fault with the camshaft synchronizer assembly. This condition can be diagnosed by monitoring knock sensor data as per Ford service bulletin #05-22-12. Replacement of the synchronizer assembly will be required to correct this concern.
https://repairpal.com/engine-buckmisfire-at-freeway-speeds-934

I hope this helps

Have you checked the ignition timing and that the automatic timing advance is working and set to give the correctly advance at the specified engine speeds. The other thing could be a carbon build-up in the combustion chambers which starts to glow when it is hot and cause the fuel mixture to ignite too early. You could also have this effect if the engine is running below its torque range (about 2500 rpm) when under load.

let me guess....... you are using regular 87 octane gas ? run it down to almost empty and fill it with super and see it it works you probably have about 100,000 miles on it the camshaft, lifters and valve springs, timing chain are all worn

My Lexus es 300 most often when engine is warm will not shift in to last gear. Stop engine start it will shift ok when engine is cool. engine pings kock senores. When in gear at high speed the car runs like new?? Car run bad in hot weather. VSC light on. Red light looks a circle with red line through it comes on not always..

Hmm, pinging is too lean a mixture or the timing is too high, or you need to run premium fuel. Did you re-jet the carbs after putting the exhaust on, if not, that is a good place to start

U can fix this by removing the one time 3 degree timing ****** shorting bar which is located next to the ignition control module, this is a common problem.

if your run no air sensor it wont rev past 3500rpm as it would not richn the engine under load