Yeah, I didn't want to admit it, but Iowa is not going back to the Democrats this election. No polls so far have shown any indication of it, and this firm is pretty friendly towards the party. The anger of farmers towards the GOP is seemingly gone and the state should start to consistently vote Republicans in, if trends are any good indication.
PPP (4/30 to 5/1): Trump +2%
DMR (3/2 to 3/5): Trump +10%
NYT/Siena (1/20 to 1/23): Trump +2%
PPP (12/29 to 12/31): Trump +3%
Emerson (12/7 to 12/10): Trump +4%
DMR is the gold standard, but they're also an outlier among polls taken in the last 5 months.
The DMR poll was taken at the near peak of Democratic division, and right around when the party was getting ready to consolidate behind the guy who Iowa Democrats soundly rejected. It was probably accurate at the time.