Rough and low Idle. Loss of Power. Miss-fire? 1986 LXi

[jjsamc]

Hello all...
I haven't been to this site much in quite a while because the car has been running good... Until now. Hope someone can point me in the right direction.
A few weeks ago when I started the car in the morning, the idle was at 500 rpm or less and rough. It used to start up at around 1500 rpm and eventually drop to under 1000 rpm after it warmed up a bit. But now it has a Putt Putt Putt cartoon car sound and feel to it at idle.
If I take it out on the streets, it seems weak and doesn't accelerate well. There's a stumbling as the transmission changes gears.
After a couple of days of driving it like this, I parked it and finally got a chance to look into it.

If I disconnect one plug wire at a time while the engine is running, I can see and hear spark at all four spark plug wells. The engine also runs worse, except with #1 cylinder. There is no change to the engine when I disconnect the #1 plug wire.
With a piece of hose to my ear, I can hear all four injectors clicking.
If I disconnect one injector at a time, the engine sounds worse, except with #1. There is no difference if I disconnect injector #1.
So I decided to replace the spark plugs which only had 10K miles on them. I also went ahead and got new set of plug wires, and cleaned the distributor cap and rotor. None of this fixed anything and I still notice no difference if I disconnect at the #1 injector or spark plug, but there is a difference on the others.
I rechecked all the above a few more times and at this point, I think I do have spark and fuel, but cylinder #1 seems to be a problem.

I will try a compression check next. And check for error lights on the computer under the seat. The PGM-FI light on the dash is off.
Any other suggestions appreciated.

At the muffler, it doesn't sound smooth but I don't see any smoke at any time.
The spark plugs I took out look OK. Plug #1 did have some brownish glazing on the white part of the tip, but not much.
Could the injector be working but clogged? The injectors are less than a year old.

[DanJDT]

Did you test spark at the end of the plug wire?

[jjsamc]

Found the problem. I swapped injectors 1 and 2. And the problem moved from 1 to 2.
I took another close look down the injector with a flashlight and could see some crud inside. I flushed it out with some carb cleaner and compressed air. And even had to use an awl to scrape some of it out. It was an orange-brown rusty paste.
I hooked up the injector to 12 volts momentarily as I blew air through it and flushed it out.
Put everything back together and now the car runs smooth again.
I replaced the fuel filter a year ago, but maybe something was accumulated in the fuel lines and ended up in the injector.
The other 3 injectors looked clean.

[Dr_Snooz]

That's some good sleuthing. Nice work.