Does this have a carb? I haven't rebuilt one in about 25 years, I recall there's a part that acts to pump extra fuel in when you accelerate quickly and may need cleaning. The float could be dirty or out of adjustment. I suppose they still make rebuild kits for carbs. Good to go with a major tune up.
I hate to tell you this, but older Grand Cherokees have had for a long time bad reputations for reliability. You can expect plenty of repairs, or sell it, and get any other brand. I hope this works out for you.