SR22 pilot reported loss of engine power during initial climb. Pilot returned to departure airport and landed.

Narrative

After the annual inspection; on departure from ZZZ aircraft experienced a dramatic loss of power and incipient engine cutoff at approximately 600ft AGL while transitioning to initial climb. ATC was advised while 'engine out memory items' executed (nose down to maintain air speed; switch tanks; check boost pump on; check mixture) reduction of throttle to under 50% restored enough power and smooth operation to return to land (at point of failure was insufficient runway for a land-back). ATC; ground emergency crews did an outstanding job handling the emergency. Cause was the connection of the fuel line to the gascolator. Nut had worked loose; causing air to be sucked in to the fuel system. The normal ramp checks; pre-flight; and run up did not detect the problem; only operation at sustained high power.Recommendations:1) Inspection/verification of security of connectors of fuel system; especially to gascolator; should be an explicit part of the annual inspection checklist for this type of system (does not presently seem to be the case).2) Given the critical nature of these connections; some kind of locking or safety-wire should be considered.3) Reduction in power should be an immediate action item in the engine out/rough checklist and memory items. Was taught that by flight instructor; but it is not in the Cirrus checklist.