Yes, the more valve overlap the harder idle is to tune. I tell most people in the build process to get their gains from higher lift rather than duration which increases valve overlap. When both valves are open at the same time the air coming in goes right back out the exhaust and is read by the o2 sensor as a false lean condition. The increased valve overlap is what causes the lumpy sound, this also causes "reversion" through the MAF sensor and makes the readings at idle erratic. It doesn't affect off-idle nearly as badly.
The OE computers usually handle up to 40 degrees of overlap well, at about 60 degrees you start bumping up idle speed to smooth things out, eventually, you end up forcing open loop at idle. Some people go as far as to remove the computer's ability for idle control altogether, I hate to go that far because I think you lose some drivability that way. But you can't expect something that is aggressively lumpy to have good street manners anyway. Unfortunately, overlap isn't a cam spec that is often published. So you usually have to calculate it yourself with Desktop Dyno or something similar. Generally the higher the LSA, the less overlap but that is not always true.