I've written an extensive paper on the topic of Yugoslavia within the Cold War but I'll try to make it a fairly concise answer (this doesn't mean it won't be long)

In short: yes, this did actually happen. However, to do with the alleged "22" assassination attempts, that's a bit harder to verify as it was likely less than that however it's impossible to know for certain with current records and accounts.

As for did Tito have this kind of power for intimidation? No, intimidation was not a factor here. To understand why Stalin did not continue in his campaign against Tito and why it looked as if Tito was intimidating Stalin we need to understand the reasons why Stalin was interested in Yugoslavia in the first place.

It's fairly common to put the reason for Stalin's interest in Yugoslavia down as being he was angered by Tito's stance against Stalin and the two's split however it was more than just that as Yugoslavia was an important European nation for several reasons. Due to Yugoslavia's geographical positioning, political climate and economic status, both sides of the cold war were vying for Yugoslavia's support. If Yugoslavia joined the soviet bloc then the Soviets would have access to the Mediterranean Sea and further access into southern Europe. Due to this possibility, the United States began to give foreign aid to Yugoslavia to help the country out of its financial situation and to win some support. This began in 1951 with President Truman receiving the green light from Congress on the matter of sending economic and military aid to Yugoslavia. Since Yugoslavia's official stance was 'non-aligned' the Soviet Union began to send out foreign aid as well so as to try and influence Yugoslavia into joining the Soviet bloc and counteract the US's attempts at political influence. This resulted in the slight improvement of the Yugoslav economy but ultimately did little as Yugoslavia refused to cut government expenditure.

So here lies the reasoning as to why Stalin ended his attempts on Tito's life. It was not because Stalin felt intimidated by Tito, but because of Yugoslavia's political importance. Stalin now knew that Tito was aware the assassin's originated from Stalin and were acting under his orders. If Stalin continued to send assassins after Tito, either Tito would begin to send others back or Tito would publicly speak out about Stalin's attempts on his life. With the Yugoslav public already feeling immense disdain towards the communist economic system, as supported by historian Anna M Cienciala who cites this as the main reason for the breakup of Yugoslavia, it would not have taken much for the US to win their support if they felt that other communist nations were attacking their leader.

This leads me onto another reason as to why Stalin would not want Yugoslavia, or the rest of the world, to know that Stalin was responsible for Tito's death as Tito was revered in Yugoslavia. Tito had a large cult of personality which rivaled those of Hitler and Stalin himself, with his death being one of the main causes of the breakup of Yugoslavia. Historian Sabrina Ramet states that Tito implemented a cult of personality upon the people as a form of propaganda so as to unify every Republic under him. Ramet says that "if you go to Serbia or Croatia or Bosnia-Herzegovina today -- even, to some extent, Slovenia, though to a much, much lesser extent -- you'll find that there is still a cult of Tito. Tito continues to be ranked as very popular among people; there's a certain nostalgia for the Tito era among the people there". Stalin's main reason for eliminating Tito was to have another leader who may be more accepting of Stalin and more willing to join the Soviet Bloc, however if the public of Yugoslavia found out that Stalin had assassinated their beloved leader Tito, there would be absolutely no chance of Stalin's plans being realised. Additionally, it would be much more likely for Tito to join the United States and accept further support if Tito felt exceedingly threatened by the Soviet Union, and so instead of showing their dominance, Stalin backed off.

Some sources:

Cienciala, A. (2002). The Collapse of Communism in Eastern Europe. [online] Acienciala.faculty.ku.edu. Available at: http://acienciala.faculty.ku.edu/hist557/lect19b.htm

RadioFreeEurope/RadioLiberty. (2010). Interview: Tito 'Symbol Of Better Times' For Ex-Yugoslavs, Historian Says. [online] Available at: https://www.rferl.org/a/Interview_Tito_Symbol_Of_Better_Times_For_ExYugoslavs_Historian_Says/2032075.html