Is it common for them to die or work erratically?

What controls them?

Reason for asking, I'm noticing how my truck runs in relation to the tach.

When the tach is basically flat line or off in la-la land, the truck seems sluggish, almost like I'm riding with the e-brake on.

If the tach is working somewhat correctly, the truck has snap, and accelerates quickly.

Am I imagining things or is there a correlation between the two?

It sounds to me like the tach is telling you that you have ignition problems.

Many of these early generation trucks have a problem with the gauge clusters going bad. I don't know the cause, but many of the listed trucks around here have gauge problems on the 96 and earlier.

That's what I was thinking, but, I'm not sure how to diagnose it. Currently the truck has new plugs, wires, cap, rotor and coil.

I think those gauge clusters even date back before the Dakota? If I remember, the same cluster was used in Dodge Lancers and LeBarons. Parts bin engineering.

Shelby Lancer dashboard

In Lancers, is the speedometer mechanical or electrical?

good question, but I don't know the answer...

I'd sincerely suspect that if the Lancer/LeBaron/Dakota was EFI of the same sort, the gauge pods would interchange.

While I haven't confirmed it, I read somewhere that '93 was the last year for mechanical speedometers in Dakotas (which is what mine has).

The pic of the Lancer dash also emphasizes just how blown out and faded the gauge assembly is in my truck...

I found this old thread while I'm searching for something else, but I have the solution. The tach on my '91 Dak was usually at 2,000 rpm forever, but sometimes zero, and sometimes whipping around like crazy. At least with it doing that, I knew the little motor inside the tach still worked. A couple weeks ago I took the dash apart and greased the speedometer cable, and while I was in there, I popped the circuit board for the tach off to see if I could fix it. This also works on old Daytonas that have a similar setup. The board is about 2 or 3 inches square and is on top of the cluster over the tach. Just lift the back of it off the main circuit board and then slide it towards the front of the vehicle (as the cluster would be installed). Look at all the solder joints. Sometimes you can actually see a cracked joint, but sometimes you just see a tiny divot in them. Fire up your soldering iron and reflow any and all questionable looking joints on the board. Make sure you don't use acid core solder. I'm not sure what the best kind would be, but I know acid core ain't it. Install the tach board back onto the cluster and put the dash back together. If none of the actual components were bad, your tach should be back in business.

well I know taht up til (and including) 93, the Dakotas were mechanical and 94-up are electronic. the 93-older have a speed sensor with a 2 wire plug for the computer AND a thread on fitting for the cable, 94+ they eliminated the cable drive.
If you see the 2 right next to one another you can tell a slightly different "font" to the odometer digits between them.
I have had 89,
90,
92 (still do)
93 (miss that one, it was a 5 speed truck)
94, and
96 (just bought, this one's 4X4) Dakotas.
so I can tell from what I remember that mine have had.
(unless it's a 4 banger) 93 was also last yr for 2 line (feed/return) fuel system and also last yr for inline fuel filter.

I have to look, I know I still have a good 94/95 computer for a V6, MIGHT still have a 93 one. Not saying that's your issue but just mentioning just in case....