Problem 1:
fixed

Problem 2:
Sometimes pulling out of first, it will make this whistling high pitched "WOOOO-ing" noise from behind the dash/firewall. Pretty sure its the 3 puct 6 spring clutch but friend said it might be the throttle cable hitting the firewall?

Problem 3:
Whenever vtak engages in 3rd or 4th gear, my check engine light will come on and it throws a code 21. The guy who had the car b4 me told me that the vteck ground cable from the ecu isnt hooked up to a proper ground (its on body right by where the ecu is). the wire is spliced and im gonna try to solder it, but i need to find out what would be a good ground for the vtec ground cable coming out of the ecu?

Problem 4: After a while when the car is hot sometimes the idle will go all the way down to like 200-300 instead of 800