I go from 12.6/0 on the hot/glow side w/key off to 12.6/10.7 during glow cycle (good batteries). All that resistance heat takes a buncha juice. You may have a coupla non-functioning plugs.
Or warm start problems might be somehting else. Failing lift pump, injection pump/fsd issues, vacuum restriction in fuel cap..etc.
Start w/check of glow plugs & replace if suspect or old (that's cheap & easy except for the contortion on a coupla cylinders; 3/8" deep socket), then check codes & repost findings if you need MORE BrainPOWER.
\'95 P30 Motorhome 16,500gvwr, 26,500mi<br />New Ipump @ 25k, boost, EGT, homemade remote FSD cooler