DBWI: Chinese Intervention in 1950 Korean War

What if the Chinese had intervened in the 1950 Korean War? How would this have modified the conflict? Would it have resulted in WWIII? Could the PLA roll back the US military? Would the US have been able to hold off the Red Chinese?

I think the PLA could own the US, to tell the truth. China has always have numbers in everything. They could have sent human waves of soldiers and forced us to pullback, or something like it. WW3? Maybe, maybe not. If it turns really bad, the A-bomb would have been use in Korea, or even China itself, but you have Russia to think about. Stalin might use this to try and move in on Europe. Of cousin, he knew of the bomb, so he might just do nothing and let Asia got hit by A-bombs.

Afterwards, it would ruin the US-PRC relationships that came after the war in the face of the USSR.

A divide Korea might be even better. At least the South or North would be far better then the very corrupt whole Korea nation we have today
I don't see why they would. Mao was busy crushing the remnants of the KMT to the south, I don't see why he'd risk everything by going against the US.
Is Stalin pro Mao?

Reluctantly. Through the 1920s & 1930s the USSR had followed standard Marxist canon that the revolution was that of urban industrial workers. Maos idea about peasant revolution had been dismissed as not properly Marxist & the Communist leaders, including Stalin had trouble shifting their focus to Maos group after the KMT destroyed the urban Communist movement in China. After Japan surrendered the USSR did give substantial support to Mao, realizing his group was the only game in town.
Here's goes to keep this in character. Mao had always been suspicious of the Soviets and had good reason to distrust them, that even after they were willing to provide air power Mao got cold feet and decided to leave Korea be.
Stalin really couldn't stand Mao. In fact if the Nationalist had beaten him it would not have bothered him in the least. As for aid the Soviets gave the PLA captured Japanese weapons. It wasn't until Stalin decided not to let the North Koreans be totally destroyed that Russian weapons began to flow to the PLA. If the Soviets had with held the use of Russian Mig 15 and 17 jet fighters who knows what might have happen.