CORAL SEA WHAT IF

      Kaga wasn't ready for sailing until May 4 do to hull damage from a reef accident and i believe the Hornet and Enterprise were close [coming from pearl after Doolittle Raid] when the Battle occurred on May 8;
Only guessing i believe Akagi would have stayed in port with Kaga; Hiryu and Soryu probably would have sailed with Shokaku and Zuikaku; but in separate 2 carrier divisions; a IJN fleet thing at that time.
      Don't think the IJN really believed they needed many carriers for that operation.
 So if the USN felt it could hold off on operations until all four USN carriers were in support of each other you might have had one big show.
     I think the Aleutian fleet plans would stay as is; some historians do believe it was no feint for the Midway operation; but one in its self.
Who knows what might have happened but it makes for some interesting scenario's.

An increased IJN Carrier presence is a game changer st Coral Sea, having more carriers means more hitting power, and Torktown was badly damaged by Shokaku and Zuikaku alone, with more strike aircraft from Soryu and Hiryu they might have finished her off. Of course, not only would it hurt Soryu and Hiryu's airgroups, but one of them could have been lost to US aircraft as well, however, the over all operation of invading Port Moresby may not have been cancelled .

My personal feeling is no midway has a much larger effect on the Guadalcanal campaign than Coral Sea...

This is most likely true; but a bigger effort at Coral Sea by both the IJN and the USN; which under different circumstances was possible, history changes;
     A little delay in starting the operation does give the IJN a possible four to six carrier operation, but also allows 4 USN carriers to participate.
Even if it was 4 on 4  the IJN sending Hiryu with Soryu [Doubtful after what Kaga and Akagi went thought in the previous six months they'd be reader or even if Japan thought they would be needed]
    with Shokaku and Zuikaku not think we have this one sided Midway type victory.  
Still think the USN would have chosen somewhere close to Guadlecanal to stop the IJN advance and the future, Santa Cruz, Eastern Solomons type Carrier battles would have happened with the same
    Attrition results;; we could they could't.

I am curious. How did the American torpedo bombers fare? I know they were outdated and did poorly at Midway, but i never heard about Coral Sea. Same result?

Midway was being planned as a follow up to Coral Sea anyway, from what I understand. Which makes sense because it'd be a logistical nightmare to plan that extensive an operation in under a month.