If I didn't know better I'd think you were describing my 95 1500SE. Easter of 2013 we took it out for a short ride and almost didn't make it home. I changed the plugs and fuel filter to no avail. I took it to the local dealer and three weeks and a thousand dollars later it at least ran but it has the same hesitation you're describing. They opened and closed the carbs four times and still couldn't get it to run smooth. I put up with it all year and called a different dealer this winter. They assured me it was clogged jets. Three more weeks there and another five hundred bucks (along with another new set of plugs) and they told me to come and get it. On a scale of one to ten they made an improvement in the one or two range. My problem sounds just like the original post. When I get between 2300 and 2900 rpm she has to decide to get up and go before she does. Even at highway speeds (55mph/2500 rpm) she coughs and flutters now and then. Mileage is good, slow acceleration is good, cram it open and she'll toss you on the back seat! She just doesn't like average acceleration! What I'm saying is, it may not be carburetor related. Keep an open mind!