Sounds like your #4 Cylinder is going bad. You may have a dead cylinder. Check the spark plug for oil, deposits, cracks, etc. I have a 96 Crown vic police interceptor and i myself have a bad #3 cylinder and bad injectors. My dead cylinder is caused by the oil ring missing from the piston. so i have an oil burner on there to keep it lasting a little bit longer. (I didn't put that there and i know it shouldn't be there, lol) But if you have a dead cylinder, time to rebuild.
I have my own question in fact, about my vic. This car sat up for 5 years (I know don't say it >.<;
and so the old gas in it turned to sludge. I wasn't aware that the old gas was in there (I was lied to from a COP about this car, so yeah i got screwed.) Anyway, so it sludged up the tank, the filter, and the injectors. I was driving down the road the other day and it just started acting like i wasn't giving it gas, but it would idle. So I Dropped a 400 dollar fuel pump job to it, got it back, and bammo, drove like when i got it again...till the next day. It started doing the exact same thing. So I changed out the fuel pump thinking maybe they didn't do it for me. Nope, still putts down the road at about 10-15 mph. The most gas i give it, the more it wants to stall out and die. So I was told by my friend's uncle (mechanic) that we're gonna blow out the fuel injectors with a little trick he learned awhile back when he was younger. The thing is, when this cars sits for about half an hour to an hour. I get SOME of my power back, but then a few blocks later, it's doing it all over again.
I'm sure it's the injectors, but if someone else knows of some other solution that may solve this problem, I'd like to know. All spark plugs are new (Running plugs too weak for the engine till i get this problem fixed, i have a dead cylinder as i said earlier) and i'm getting good spark to all plugs. Codes read random cylinder misfires on 1, 3, 5, and 7, but never all in the same reading (cept for 3, that's the bad one)
Thanks in advance.