88' Ram 50 Revival

So i recently got an 88' Ram 50 4x4 (has the 2.6L I4) that sat for at least the past 12 years without running (last registered in 2000). The body is in perfect condition, the engine would only turn over and not even try to start. I've put in a new distributor cap, changed the oil and filter, new fuel filter, put the firing order in correctly (was at 1-2-3-4, now at 1-3-4-2) and pulled the jet valves, as one of them was so covered in carbon build up it wasn't springing back like it should, and put in an eliminator kit. All of this has helped and it starts up and will run, not well though. It has a bit of backfire out of the carburetor, and wont idle at all. It starts hard, shudders a lot, and will only stay running at higher rpm's. This is a pretty broad problem, but I'm fairly stuck on what to try next. Any suggestions?

If it's back firing out the carb, this is a timing issue. Apparently when the combustion chamber fires an intake valve is still open and the explosion back tracks up through the carb. Have you done a compression test on the motor? The trucks timing belts are rubber and should be changed 60k to 80k. These belts can jump sprocket teeth sometimes and throw timing off as well. Backfires up carb are a bit dangerous so careful putting face near carb when it is doing this stuff. A burnt valve can also allow an escape route for a backfire, but burnt valves in these trucks are rare. The biggest factor with our trucks is overheat and cracking of heads between valves or MCA jet valves. Hairline cracks are common and fixable though.
Being down for 12 years is incredibly long. There must of been a reason for letting the truck sit so long and your probably going to have to locate this reason. Sitting still like it did can cause a series of issues, gummy gas, dirt in tank, clogged filter, PCV valve stuck, besides maybe a vacuum leak and the reason it was made to sit un-used. Most people will not let a working vehicle sit for so long. The Mikuni carb is no doubt one of the harder carbs to work on and sitting does not do it very well. Most of us have changed to the Weber and it will give your truck the best performance upgrade. Removing the jet valves is a good thing at this point.
Try a compression test, that will give you the health of the truck. Set your timing correctly, because backfires are an obvious timing problem.
Post some photos also if you can. Many times we can spot an issue in the photo plus we like to see what folks have for their rides.

Welcome to the Forum :)

So I did a compression test before the jet valve elimination kit was put in, at that point it the compression was at, cylinder 1 was at 20-30, cylinder 2 was right at 120, and cylinders 3 & 4 were at 50-60. After the kit was put in, all cylinders but 1 were at 150, cylinder 1 was at 0. I'm not sure how it went down in compression. So at this point I'm fairly sure I will have to replace cylinder 1's valves or rings. My dad did just tell me that I have a relative that went to school specifically to work on the 2.6L, so I'm going to contact him for a bit of help/advice on what to do next. Any suggestions on how to test if it's the valves or the rings would be greatly appreciated.