Car feels sluggish lately, worth doing injectors before a long drive?

[yardleybickford]

Planning a road trip to Salalah next month with the family and I've noticed the Grand Cherokee just hasn't felt as punchy as it used to, especially on inclines where it used to pull without effort. Fuel economy is down too, maybe 15 percent worse than last year on the same routes. Nothing dramatic, no misfires or warning lights, just a general sluggishness that's been creeping in. I've done plugs and air filter already so I'm thinking it might be the injectors getting clogged up after years of whatever fuel I can find. A guy at work mentioned he got a fast fuel injector cleaning service done somewhere and said the difference was noticeable within a day, which sounds appealing since I can't afford to have the car sitting for a week before the trip. Do these cleaning services actually restore performance or is it mostly placebo? And would it be smarter to get it done before the long drive or wait until after?