It is really common for the timing to get done wrong on these trucks. I had one that I fought with off and on for years that never ran, until I swapped around the plug wires. If you have two cylinders out of 4 that are not firing, it takes 30 seconds to trade the plug wire positions on the cap and verify nothing is backwards. If no change you eliminated something, swap back and move on. I've had a LUV that I had to do this to, and once picked up a very poorly running Volvo 4cyl that ended up running great after swapping two plug wires the dreaded prior owner had wired wrong. The point was that it is very easy to check and eliminate, and totally would explain the problem you are seeing.
I'm a bit curious about this carb you have. It doesn't sound quite like anything I've seen on a LUV before. Any way you can get a few pictures of that up here? I've seen Webers and rebranded Webers, but that is about it. I think I've heard the name Elkton associated with Motorcraft before, but I don't know about the part number. I think there was a version of the Weber 32/36 made for Fords that was rebadged as a Motorcraft part number, 5100 I believe, and I think it bolted straight to the intake. There is also a Motorcraft 2100 that might bolt to the Weber adapter plates that fit a LUV. Both are 2Bbl carbs though, so who knows what you have there. Pics, please.

As I been saying a while, compression test will eliminate or confirm most all of the worst causes of the problems you have. Once you have those numbers you will know if it is even worth proceeding on this engine or if you need to really tear into it. Plugs, wires, spark and fuel are irrelevant if you can't get above about 60-70PSI of compression at the LEAST.
Oldestisuzuist has a lot of good tips and techniques for puzzling out what is going on in the engine. Those tips for figuring out intake vs exhaust valve problems remind me I need to get a remote starter button.

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95 Isuzu Trooper Daily Driver
86 Isuzu Trooper reliable backup
77 LUV 2wd stock beltway blaster (resting)
79 4x4 LUV project: 2.6L, 5spd, 31s (eventually)
MEPR: Man, my 4x4 makes all other LUVs look good
