Backfiring and skipping

When was the last time it received new spark plugs, plug wires, a distributor cap, and rotor? Because it sounds like it is time for a tune up. Let us know.

Bad wires can cause the car to run badly. They could be cross firing, where the spark jumps from one wire to another because the insulation is old and weak. It could also be that you switched wires by mistake. Attached is the firing order for your engine. Please double check that you have the wire correctly connected. If that is not the problem, then I would suggest changing the wires, as they likely need to be done.

Also what plugs did you use? The wrong plugs can can cause the car to run like crap.

Is it possible that the distributor got turned a little bit when you were working on it? An adjustable distributor, like the one in your car, could easily cause the poor running that you're describing.

It might be too advanced. Turn it back just a hair and tighten it down. See how it does. If it's not in the ignition system, then the next thing I'd think about would be the catalytic converter. The simplest way to check it is to take the upstream O2 sensors out and run the car to see how it does. It'll be loud as heck, but if it feels much better, it's because there's no back pressure restricting the flow of exhaust through the cat.

Ah well it's not that then. Next thing I can think to check would be the fuel filter and pump. If you haven't replaced the filter in a while, go ahead and do it. As far as checking the pump, we have a how-to guide for that. https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

You can borrow a fuel pressure tester from AutoZone for free (just pay a deposit, it gets refunded when you return it). I'm also attaching ALLData's guide on checking fuel pressure. If you decide to go with the pressure tester method, you should get 5.5 to 6.5 PSI.

This is a different expert. The first thing I would do is a complete compression test. If you find any weak cylinders, do a leak down test.

This engine is pretty famous for wearing off cam lobes. A broken valve spring will give you those symptoms also. They have also been known to pull out the rocker hold down stud.

May be a weak valve spring, ok when idleing but at higher speeds not strong enough to keep the valve closed when other cyclinders are on compression stroke. Using a test light short out each wire at the spark plug while it is reved u a bit. Shorting out the plug, you will hear a difference on a good cylinder and there will be no change on a bad one. We used to do that years ago and I learned it from my father.

You can also do something called a running compression test, when you remove the shraeder valve from the tester and run the engine. That will show up things like that.

You can change a valve spring without removing the head using compressed air.

Yes, you would have to replace it. You can usually see something like that by watching the rockers but if necessary you can measure the lift of the cam lobe. You would also have a loose rocker clacking if nobody cranked it down.