This car is giving me fits. It has a hard shudder which feels like a bucking under load from 1/4-3/4 throttle. Also has a knock sensor code but absolutely no audible knock and a brand new knock sensor. I have replaced plugs, wires, fuel pump, filter, cleaned man, cleaned injectors, run scanners on it and all data looks good. It also has a random hard start issue where it will start and stall, then fail to restart for around 1 minute then sputter to life. Its very hard to drive. It is also my only transportation so I need answers right away! Thanks in advance