Hey all! So there is this 03 2.3 with some issues: When it warms up to appropriate temperature it begins to sputter, a lot of smoke coming out of the exhaust, and smells like something burning. It’ll sometimes not go faster than 20mph also. Mechanic says that it’s only happening when it reaches a certain temperature.

They’re pretty sure it’s an internal engine valve. Otherwise could be catalytic converter. One of the catalytic convertors was changed in January, so the mechanic who did the work doesn’t think it’s the converter since he tested both of them and it was fine.

the valve cover does leak into the plugs and the pcv hose needs replacing.

What internal valve could could be causing this?

thanks!