MeYou might try putting a receiving blanket in between you and my husband have tripletsyour baby while you hold him as he falls asleep. Babies notice the loss of body temperature when they get put down in their crib, so if you let the blanket absorb the warmth and I mention that notkeep as much contact with him as you put him down, the blanket will help maintain the temperature he fell asleep to one-up anybody.
On a related note, butthe 1.5 hr times you're encountering sound VERY similar to highlight how desperate we were when wewhat my husband and I encountered much the same issue when our girlstriplets were about 3 months old. We spent at least 2 morerelentless months rocking and burping COMPLETELY AWAKE babies for 1.5 - 2 hrs a night and it was driving us insane.
We had a night time routine that started at the same time every day: bath, story, bottle, burp...and burp, and burp, and rock, and rock, and oh my LORD. They just wouldn't go down. They had this issue with naps sometimes, too. Always in 1.5 hr bouts that spiraled the whole day. It was just awful.
In total desperation, I read this book: The 90-Minute Baby Sleep Program
Very basically, babies have a 90 minute rhythm that we were missing. We had no idea we were overshooting their sleep window, so when we did not get any one baby 'down' 80 minutes after they first woke up, their next 90 minute cycle would kick in and BLAM: we ended up burping/rocking/etc. until they hit the next sleep window (80 minutes later).
And that's how you end up with a baby that's awake for nearly 3 hrs straight.
This book changed our life. I HIGHLY recommend it. It's straighforward, easy to read, talks about CIO (pros & cons, what it really is, how to do it effectively if you choose to try it) and how kid's sleep schedules change as they age (provides schedule examples).
Having first-hand proof that this method absolutely worked, I think this book could make a world of difference for you.