No start with a shudder:(

[97gtp]

I have replaced all these things: spark plugs coil packs, coil pack wires, new ptu relocation kit from z1. I just bought a cas and I've checked the timing belt. A fuel injector and I've done the resistor trick to the car to the knock sensor bs- I've been doing nothing but trying to get this car to run normal since I bought it, and as soon as i have narrowed the issue of dead cylinders down and I take it to complete the new coil pack install and replace a proven bad injector, on start up now it won't start...

The car was sitting for about a week so when I got home and fired it up it kept wanting to die at idle, so I had to keep revving it to keep it alive at stop signs and stuff. I thought maybe it was a battery issue simce it sat for a while and with all its issues it never gets driven anywhere far. so i took it on the free way (in hopes to let the alternator charge the battery)and when i got off the freeway it was still doing the same thing. not quite as bad but it would still get low on the idle and wanna die. So I parked it and put in a fuel injector to solve my dead cylinder problem. I went to fire it up and when i did it then Made an abrupt clank noise and stopped. I Tried to start it again and it wouldn't even put the same effort as it did at first. it just sounded like the engine wouldn't turn at all. If it sits for a while it would give one good effort and the shudder to a halt. And repeat the same thing as I just mentioned. After this I received a code 11 and that's when I bought a used good condition cas to see if that solves the problem. It did not, it did the same thing, Tries to start for a second then a loud clang noise and it stopped then every attempt after just seemed like the engine couldn't turn over. I have no clue what the hell is the issue I can check fuses maybe check some relays. Right now after installing the cas and clearing code 11, I have 55s I tried starting it several times and still 55 so I'm not sure if the obd will pick that up since the car hasn't fired up completely or if it just reads 55 because I replaced a bad cas. Does anyone have any ideas to what this clanking no starting crap could be? Please help!
I have a 1990 300zx na 5 speed t tops