I have a question to ask.

95 SE with 240K on it.

Injectors new (remanufactured) & Coils new (Hitachi). Entire front suspension components less than a year old with quick struts. Left & Right engine mounts new. not replaced the front (passenger side) & transmission mount yet.
Plugs are new NGK.
Compression test was ok.

It keep on having misfire on cylinder 1. Not continuous.
CEL comes on. I can feel misfire (shaking).
Sometimes, car drives fine without misfire. Sometimes it misfires for a while and stop.

When in reverse it shakes a lot more.
When going on to highway while it idled smooth (no misfire), it runs good. Then, CEL pops up anywhere above 45mph blinking.
When I leave the car on idle (parked), CEL pops up sometimes after 4 or 5 minutes. sometimes after 10 to 15 minutes.

Everytime, it is P0301.

What should I look up?

 

Make sure your injectors are spraying correctly, I had that issue back in February this year when I installed new injectors. They were stuck open. After correcting that problem, It runs smoothly after 7 months.

 

Blinking CEL indicates major misfire. Per the FSM, it's not good to drive when the CEL is flashing. Replace injector #1.
I doubt it's the coilpack, but as a quick test, swap coil #1 with coil #3. Reset CEL. If code is still p0301, it's your injector, if code changes to p0303, it's your coilpack.

 

I drove with the CEL blinking for 15-25 miles or so after the new injectors were in. Not a fun experience at all. Haha. Even though it's pretty bad to drive it with it blinking, Do no more than 50-75 miles with that... lol.