My 6G74 SOHC Diamante has a really poor idle.
Does so in D, R and to a lesser extent in N.
Things tested to be fine:
ISC (idle speed also fine as per computer data logging)
All spark plugs
Air filter, fuel filter, oil filter and oil
Valve cover gaskets
PCV valve cleaned, TB Cleaned
Idle gets quite bad after long running times.
At some stage it felt like it idled better after cleaning the PCV and changing rocker cover gaskets but poor idle returned (could have been coincidental).
It feels almost like it sporadically misses and shakes the car.
Drives completely fine and engine is smooth other than at idle.
Any advice would be greatly appreciated.
2003 Mitsubishi Diamante 6G74 3.5L. 5 Speed auto. 137,000 miles