Well i dont know if this will help but i had a similiar issue like this and there was a vaccum leak amd it toom me three months to find. One of the elbow connectors was cracked and after it heatd up became plyable alowing a vaccum leak. Instead of buying the hard plastic vaccuum line a bought the plyable inexpensive rubber vaccum line which i was able to connect right into the inputs not having to use the elbows. It is very inexpensive at autozone like a dollar and some change a foot. I bought like six feet of it for like under ten dollars. Took of all the hard plastic line and elbows and pluggef right into the connections. Whether its the egr or the fuel regulator the line fits right on with a little spit. Lol. I love the soft plyable line better and it fits very snug just get the rigjt size. I changed all my vacuum lines with this stuff under ten dollars and elimated the hard plastic with all the elbows and connectors and it solved my problem. Hope this helps. Only took me three months to find. Lol.