I have a 91 4 runner manual sr5 3ltr. it has a hesitation, lacking power, late valve timing and lean mixture what is the problem. changed plugs, leads full service and tune new disy, new fuel pump and filter.

These code cover a few different areas. You might need to get a Good mechanic to look at the vehicle.
p1519 - Intake Manifold Runner Control (Stuck Closed). This will affect your Fuel air mixture and might explain the high revs. This is a valve controlling fuel/air flow to give an even flow at all engine speeds.
Codes p0171 and p0174 both refer to the fuel mixture being too weak.
The p0741 is on the Transmission. There is an issue with the torque converter electronics.

p1519 - Intake Manifold Runner Control (Stuck Closed).
p0171 - System too lean, bank 1.
p0174 - System too lean, bank 2.
p0741 - Torque Converter Clutch Circuit Performance/Stuck Off.

pinging ( detonation) is from lean mixture ( white smoke)( heated oxygen sensor/s in the exhaust manifold /s), incorrect ignition timing
The lack of power could be a valve timing problem from the advance mechanism being faulty
best to have the fault codes read to determine the problem area first

Yes. A vacuum leak pulls extra unmetered air into the intake manifold, which leans out the air/fuel mixture. A lean running engine can cause hesitation.

Did you check the vacuum lines and also unhook them when you changed the timing?

have you changed fuel filter lately as that sounds like the problem

Fuel supply or valve-train issues come to mind.
If the fuel mixture is lean, that will cause backfiring and loss of power. Poor fuel atomization caused by incorrect pressure or plugged injectors should be considered.
Cam timing is a possible issue. Has the cam drive slipped?
Best wishes!

The o2 sensor is a used for fuel trim, If you continue to run the truck with a lean condition, your likely to burn a valve, but a vacuum leak can cause a lean condition, and with the RPM acting that way, I would really check for a hissing sound on all the vac hoses, intake manifold, power booster, ect.. it won't hurt to check the fuel pressure, and if you remove the spark plugs you can read them for the lean condition. good luck

Check the timing and compression. Get a shop manual for your car and use it to set up the mixture adjustments properly. Crossing the HT leads out of order did not cause any damage.

I might be able to help you on this. I will you two options
1.Sounds like your fuel mixture is too lean or breather pipes from inlet manifold are leaking or idle sensor valve faulty.
2. check your clutch sensor. It might be disconnected. this also leads to engine stalling problem

Something is riching or leaning this vehicle out at the wrong time. I'm gonna go with ERG valve being stuck in the open position. The only time this thing should work is at crusing speeds. Once the car has cooled down the fast idel cam takes over and prevent it from stalling. Once temp is within range idle cam stops and EGR is dumping into the mixture.
Use shop manual to do proper testing for the valve( probably a hand held vacuum pump is all you will need and gum out to free it up but you should properly replace it if it turns out to be the culprit.