Engine performance lags, won't rev above 2500-3000 RPM.
This is in park or neutral.
In driving, it has a hard time revving above even 2000. At that point it acts like it is going to stall out, like it is fuel or air starved.
Engine idles real smooth.
Vehicle accelerates very slowly because of engine problems.
The previous owner was replacing the heater bypass valve and broke the back hose on the CCV system, and the CCV hose was replaced by me.
She said this problem started right after that she broke the hose... she doesn't know anything else about what could have happened...
It is like something is holding the engine RPM down.
What I have checked or replaced -
fuel pressure and regulator.
Timing not adjustable but it IS advancing with RPMs.
Engine codes point to lean fuel mixture, TPS code, and MAP sensor code.
MAP and TPS are both good.
compression reads 120
Fuel injector resistance measures 14.9 ohms each.
Engine does not seem to be consuming any anti-freeze or oil, no weird color smoke out the tailpipe.
Trans fluid good and up to level.
Gasoline of a good grade.
The vacuum pressure holds steady at 14 PSI which is a couple pounds lower than it should be. This is a sign of a leaking manifold but even after the engine shuts off, the vacuum holds for a while. How bad could it really be leaking if at all?
OK so the last thing I can think of is maybe the catalytic converter is partially clogged but have not disconnected it...
And with not knowing for sure how it ran before the CCV mishap...
So what else could possibly cause this problem? How would a catalytic converter get clogged to begin with?
Truck has 201,000 miles and was not maintained the best.
4.0 engine, 2WD only, auto,