just did this repair last night. Total took 2.5 hours. I'd completely suggest removing the cowl. Way easier. Second, I'd suggest removing the firewall side vacuum, electrical lines after removing the plenum. Easier to see what you are doing for sure. Lastly, I took an empty egg carton bottom, numbered it 1 - 12 and used that to hold the plenum bolts. The 13th, 14th I just set beside but it really helped keeping them straight for reassembly. As I've said in other posts about this same procedure, the isolator bolts and plenum cover all get torqued to 89 in-lbs. I did them in steps of finger tight, 50 in-lbs, then 89. No broken parts
