1992 Toyota Corolla Intermittant problem of only running on

Car runs perfect most of the time. Did lots of work before daughter used it this summer for sales job out of state. Replaced plugs, wires, cap, rotor, battery, air filter, fuel filter, and other things I don't recall right now. She was driving mid summer and car lost all power. Has it towed to repair facility. It ran perfect when it was there but they wanted to be sure. They replaced fuel filter and said it was pretty dirty (seems strange to me). Ran fine except for an occasional hiccup. Had her put fuel injection cleaner in tank and seemed to be OK. Until 2 days ago. It stalled and she could not get it running. I went to see what was happening. It was running very roughly on cylinders 3 and 4 only. I determined this by unplugging fuel injector connectors for cylinders 1 & 2, and engine ran same. No moisture in distributor cap. Decided to disconnect fuel line to fuel rail and pump some gas into a glass jar. It was clean, no water or debris but I have no idea what type of fuel pressure was developed. Got it home, verified spark at cylinders, used noid light to verify signal was getting to injectors. Checked resistance across all 4 injectors, they were right around 140 ohms each. Tried to see what would happen if I disconnected injectors 3 & 4. One of the cylinders tried to fire but it never started. Hooked up #3 along with 1 & 2, still would not start. Removed back seat, cover plate to tank, only had float switch but gas and tank I could see looked clean. I guess getting to the the fuel pump requires dropping the tank.
. Possible things for me to look at, I think, are: change fuel filter again, pull fuel rail and examine/clean injectors, have someone check fuel pressure, pay to flush injector cleaner through rail. Looking for other ideas I can do myself as I am "between jobs" and have time but little money right now.