I can't tell how much 'shudder' you're feeling ..if it's beyond what mine has (very little) ...from sitting here at my computer desk. Maybe your shudder is more than some of us other guys experience in our pickups. But since you indicate it goes away when put in 7th that means that it's definitely there. Maybe yours is slightly worse than what mine feels. Mine has some, I just know from experience when it would normally occur and at that point I generally pre-kick the throttle down and it usually kicks it off w/o the shudder. And for local driving I just put mine in the lower gear.
Maybe it's worth (despite what the mechanic advised -- maybe he just didn't want to 'get into it' on your truck) look at some basics. Pull your truck's spark plugs out for inspection and ohm them out, in case some are worn or one has a cracked porcelean or damaged internally. Sure plugs could work 'mostly' but at times a damaged one may not spark well and lead to a shudder. And spark plugs can fail. Even brand new ones out of the box can be dead sometimes ...out of the box! (had it happen 2x). New spark plugs sometimes fall onto the shop floor during installation. Mechanic picks it up ..blows it off, looks around (good, nobody saw my mistake!!) ...and installs it in the engine (maybe it broke internally??). Inspect each plug as it's removed. They tell a story. Note the color and condition. A very clean plug could indicate a bad headgasket. An oil-fouled plug could indicate a bad valve guide/ring and so on. And while you're at it, also ohm out the coils. They can go flaky or get weak as well, regardless of age. Either the coils or the plugs are simple and cheap repairs which could *definitely* definitely cause a greater amt of shudder feel.
Secondly, if it were me, and I had all the spark plugs out of my engine, and I was trying to get to the bottom of a shudder problem, I would take the extra 1/2 hour and perform a complete compression test (engine warm of course). It's hardly any extra effort while the plugs are out (only one plug removed from each cylinder). Write down the results of each cylinder and compare them to each plug, per it's cylinder. Doing these things you can begin to rule out possibilities. That's called basic troubleshooting.
It's entirely possible your engine has developed low compression on one cylinder, or a burnt valve, a cracked injector o-ring, or maybe a failing head gasket. For example, on my DD (not the Ram) while doing the plugs I did a compression test and discovered one of my cylinders is quite low on compression. It seems to be a burnt valve. Looking at the scanner, I DO get quite a few misfire counts on that cylinder at idle, but not enough to cross the threashold and light the "Check Engine" light. And during normal driving I can't tell there's a low cylinder. But it does have low compression on one cylinder, that's a fact. That's the kind of thing you would like to know about if it exists on your pickup engine.
Another thing you might do is to run a can of injector cleaner in your next tankful. And do a vacuum test ...clean or replace your truck's MAF sensor. Ensure the PCV is good, the hoses aren't cracked or rodent-chewed (it happens!!), and the snorkle from the air filter box to the throttle body is on tight and 'right'. I've seen it before where a previous mechanic installed the rubber snorkel quick and folded it under the clamp at the throttle body (you can't see back there) ...and therefore it was sucking in some 'fresh' air which was not going by the Mass Airflow Sensor (MAF) ...which was thus throwing the computer's fuel/air off a little. Is the throttle blade carbon'd up? (that's an often overlooked maintenance task). Has the temperature sensor drifted a little (that would throw off the air/fuel)? Of course make sure your truck's air filter is clean (no mice nests underneath it). If you're running 87 gas, try running 89/91 and see if that helps.
So, there are a number of things that could contrubute to excessive shudder which you could check and rule out before condemning your pickup. Just because the mechanic said, "They all do that" ...that's one mechanic's opinion. Maybe he was up to his eyeballs in good-paying work, and didn't want to spend umpteen amount of time chasing a ghost that might or might not be there. Mechanic's like quick/easy repairs that pay money ...replace this part, BOOM...out the door, get paid ..NEXT please! Long troubleshooting work like this might or might not lead to improved driving, and how many times does he want the customer to keep coming back complaining when he's working flat-rate? (not getting paid the 2nd time)? And customers really complain when they pay for 4 hours of inspection labor and the problem doesn't get resolved. So, that could be one reason he didn't want to take on that job.
In summary, it might not be a bad idea to check some of the things I've outlined above to rule shudder-possibilities out. That's what I would do if it were my truck.
