I hear about replacing the egr o ring or tube gasket, what is this

 

The EGR(exhaust gas recirculation) valve on the intake manifold and its tube to the exhaust manifold often need to be removed when other engine work is being done.
It is recommended to replace the seals(gaskets or o-rings) when reinstalling.

Or, obviously, if you have an exhaust leak at those locations.

 

I just go back from doing a code scan, no codes, but it pings worse on 87 than 93 , should I try different plugs or go straight to the knock sensor, thanks and the engine has unbelievable power, more than my 99 4 liter sohc which had a five speed, this truck flies for a 4x4, but I don't abuse it,, it runs too good, thanks

 

The 4.0l SOHC does have a Knock sensor, so if your engine is knocking/pinging then yes, replacing the knock sensor, which is hard to get to, would be the first step.
It shouldn't ever knock if knock sensor is working.

The 4.0l SOHC has 9.7:1 compression so will ping on most regular gas, that is the reason the knock sensor was added, it allows the computer to get the most power from the engine right at the edge of pre-detonation(pinging).
4.0l OHV had 9.0:1 with 160HP, SOHC has 207HP

Knock Sensor data is available with a live scan, look for KS
If working you should see a negative number constantly changing a bit, -4 is average I believe.

 

Thanks Ron, will most scanners do a live scan

 

Most do.

Google: obd ii scanner with live data

There are also wireless Bluetooth adapters for OBD II they send codes and data to smart phone or laptop via Bluetooth

Google: obd ii bluetooth

I can't recommend any but reviews can be a great help