BTW, the "check engine" light does not come on. I just drove round trip to San Diego (about 20 hours driving) and put injector cleaner in with each tank of gas. No effect whatsoever.

I've also changed the fuel filter, air filter and checked the coil-on-plug connections.

Just noticed I've got 59,382 miles which doesn't leave me much warranty time left. Luckily there is an Isuzu dealer in Ukiah, CA where I work.

Don