A good pug group?

On Friday night, and again on Sunday night, I pugged a group as healer for ZA.  I had read up on the fights, but otherwise didn't have a clue.  I had heard that the fights were tough. 

On Friday night we didnt get the third boss down. 
Got the first boss down, then the tank immediately quit.  Second tank joined, complained about low DPS during second boss (failed attempt) and quit.  We got another tank that immediately went AFK.  Booted him got a second group.
Struggled our way though the second boss, and ended up with only one other DPS and myself remaining in group. 
Finally got another group together and we tried the third boss (with whelps) twice.  There was soo much damage being thrown around, most toons on very low health, and me with no mana.  One of the DPS took 25% of the total group damage, only just below the tank.  His DPS may have been the best of the group, but I could not keep him up as well as the tank.  I apparently didn't have the mana management to the satisfaction of the group.  To be honest - with that group, I agreed, and left. Feeling somewhat downhearted, and swearing off PUGs.

However, Sunday night, I thought I would try again, fail again.  There is something to be said for the banging your head against a brick wall method of progression.  Got up to the whelp boss and wiped once.  Wiped again on a bad trash pull.  There were a few indvidual deaths in the rest of the run, no one left party, and it went well.  Total run time : 90 minutes.  I was astounded and very pleased. 

Oh, and as an aside, apparently I don't pug many 5 man dungeons.