Going from 10.2.x to 22.214.171.124 I have often noticed two points:
First, you must re-gather system statistics. If you run
select * from sys.aux_stats$;
what do you get? Have they ever been gathered? I suspect the 11.x makes more use of them than earlier releases.
Secondly, the default for serialdirect_read is now auto, in 10g it was (I think) false. This can have a big effect on pushing the optimizer away from indexes.
Pl post EBS related questions in the EBS forums - https://forums.oracle.com/forums/category.jspa?categoryID=3
Pl confirm you followed all of the steps in this MOS Doc
Interoperability Notes EBS R12 with Database 11gR2 [ID 1058763.1]
Pl do not change init.ora parameters randomly - they need to be set as per this MOS Doc
bde_chk_cbo.sql - EBS initialization parameters - Healthcheck [ID 174605.1]