At this point they are considered incertae sedis;in other words, we know that they are theropods; and probably coelurosaurs; but we don't know who they are related to or how they fit into the big picture of theropod phylogeny.
Idle speed is adjusted by means of the idle control valve, which is a solenoid-operated valve that is generally automatically adjusted by a computer. One problem that can occur with this component is a loss of power (from a severed line or a short) but a more common problem is simply dirt and grime.
SMOOTH idle is as smooth or almost as smooth as a stock OEM engine and has high manifold vacuum, 18 inches or more. These engines work well with the stock exhaust system and torque converter but all engines benefit from a good performance exhaust system and a higher stall torque converter.