I recently bought this 4runner with cracked heads so long story short,I have never driven this 4runner t know if it had any underlying problems ,obvious or hidden .I had the LNG block rebuilt and got it all buttoned up and now has a stumble like a wet distributer at low rpms,it's there at higher rpms but not as obvious.
I have replaced the cap,button,wires,fuel filter,PVC,o2 sensor,all grounds are connected,fresh fuel and air filter.all these we're replaced with the new engine.
What is strange is pulling #1 plug wire effects nothing,it runs the same.pull any other plug wire and the motor runs like crap.I have checked plug and it is darker colored than the others and does not smell of fuel at all.I can reach down with a long screwdriver and can hear the injector clicking at idle .

 

just checked compression,my gauge does not hold but it bounces up to the 170 range on the 3 cylinders i checked,spark plug in affected cylinder was not sooty but just dark like nothing is happening,the other two cylinders that I checked the spark plugs looked light brown.Might be the injector is clogged or something.

 

Are you gettting spark to that cylinder? Bad wire? Bad plug?

 

Seem to have good spark and all wires and plugs are new

 

Well it turned out that one of my injectors was only putting out a fraction of what it should.I got them all cleaned and it runs like a champ.no codes so just had to track it down the old fashioned way.