95 Isuzu Trooper hesitates uphill

I have a 1995 Isuzu Trooper with 92,000 miles. I was driving back from Ojai to Los Angeles last weekend and noticed when I was going up a steep hill, it felt as though the car was hesitating, as if it could die but then it would go. Now it has been occuring on a daily basis. When I start out, I accelerate and it kind of has this air pocket thing. Does it sound like a fuel filter problem? Or could it be the trans? Or spark plug? I don't know but I'm wondering if this problem can be checked through a diagnostic. Any suggestions or ideas would be greatly appreciated