passenger door keyless entry problem

My 94 Camaro Z28 has developed a strange problem with the stock keyless entry system. It is very flaky, working sometimes and then not working later.

When I press the keyless remote twice to unlock the passenger door, sometimes it will not unlock. I have checked the door lock itself, it is not binding or jamming and works fine manually or with the lock/unlock switches inside. The drivers side always works fine with the remote. This has just started recently, I have never had this problem before a few weeks ago. I have changed the batteries in the remote, but this did not help. However, the passenger side will lock fine with the remote, it just doesn't always unlock.

Anything else that I might look at besides the keyless entry module? I can't think of anything else, but maybe someone has had this problem before and has a simpler and cheaper fix.

Does it unlock the drivers door every time youi try it, with only one press of the button?  Have you tried pressimg unlock 3 or 4 times?  You could possibly have a bad switch or dirty contacts under the rubber membrane. 

-------------
Let's Go Brandon Brown. Congratulations on your first Xfinity Series Win. LGBFJB