Tocata TB-20 pilot reported several momentary loss of engine power events during cruise. Pilot diverted and landed without incident.

Narrative

Priority handling report.ZZZ2 to ZZZ1; with a divert shortly after takeoff into ZZZ.Pilot; CFIIMEI/ATP; Current and Qualified with Flying Class I medical and recency of flight experience required for Day/IMC flight. Aircraft equipped with Garmin GTN750 with current database and Foreflight; STRATUS; with Jeppesen backup charts. Aircraft - current annual and IMC certification.Prior to flight; aircraft was hangered in a heated hangar at ZZZ2; with 10qts of oil; and 60 gallons of fuel. Last flight was ZZZ1 to ZZZ2; refueled by adding 40 gallons at ZZZ2 the afternoon 24 hours prior. Fuel was checked during preflight with no contamination. Fuel was also checked at the fuel farm twice on Day 0 with no contamination or water found.Took off at XA:50; on an IFR hold time clearance from ZZZ Approach; cleared direct ZZZ1 7000 heading 180. Aircraft free of snow and ice. Contacted ZZZ [TRACON] twice passing 1700-2300' cleared direct up to 7000. At 5400' with negative icing on departure; visibility was limited to 1-3sm with light snow. Updated cruise altitude request with ATC to stay at 5000' to avoid climbing into the cloud layer. Conditions - light snow; negative icing. Cruise checklist included leaning mixture from 20.3 gph to 15.0 gph at 2350RPM and 23.5inches Manifold Pressure; electric fuel pump off.Approximately 330/10 from ZZZ; GTN750 GPS lost satellite connectivity for 2 minutes; then reacquired navigation solution. Aircraft has flown over 300 hours around the US and Foreign airspace and has only ever lost GPS connectivity in and around ZZZ. GPS interference has happened and been reported to ATC multiple times. Pilot expected satellites to return and monitored reacquisition of satellites on the Garmin 750 GPS status page.Engine lost power for approximately 1 second and then surged back. Respective Fuel flow was indicating 9.5gph; IAW (In Accordance With) engine loss checklist; pilot moved mixture full rich. Engine power was restored; but fuel flow was limited to 15gph; 5 less than expected. Pilot turned electric fuel pump on with no effect on fuel flow indicating a restriction in fuel flow.GPS Navigation lost again at that moment. Pilot asked ZZZ1 Approach for an immediate vector to ZZZ; they responded that ZZZ was IFR with 1 mile visibility in light snow and recommended a GPS approach. Pilot replied negative; GPS lost; request direct vector for VFR landing. Conditions were VMC with positive ground contact sustained for entire flight with flight visibility ranging from 2-3sm for the entire flight from ZZZ2. In flight visibility at that moment assessed as 3sm. ATC acknowledged cancelation of IFR; immediate vector was heading 160 direct to ZZZ for visual approach to Runway XX. At approximately 350 for 6 miles; ZZZ advised that min safe altitude was 1500'MSL and aircraft was clear of all obstacles at current altitude of 1400'MSL. Engine lost power again for 1 second; so pilot delayed slowing and lowering the gear and accomplishing the remaining items (flaps/gear) of the before landing checklist; until 3nm out (estimate because we had no GPS). Pilot lowered gear and increased power to hold altitude at 100kt when experienced a loss of power again for 1 second. Pilot increased power to hold speed just under 129kt (gear speed); with gear down and locked; flaps set to approach IAW before landing checklist. Pilot asked Tower for runway update and needed a 3-5 degree turn correction to the right.With runway in sight and assured; pilot slowed to 100kts and lowered flaps to full; landing without incident. Aircraft cleared the taxiway; exited at FBO. Pilot turned electric fuel pump off in accordance with after landing checklist and the fuel flow did not change; indicating a functioning engine driven fuel pump at idle power. Systems analysis would indicate a fuel system degraded fuel pump; obstruction in fuel line; contaminated filter system; or limited air intake into fuel system due to snow.Human Factors - GPS loss of navigation at the moment of divert and limited flight visibility due to snow combined; significantly hindering situational awareness resulting in dependence on air traffic control for the divert navigation and terrain avoidance. With less than 6 miles from a viable runway and 3 x temporary losses of power and marginal VFR conditions with no horizon; pilot elected to maintain aircraft control; analyze the situation; and take appropriate action not to delay approach and landing to reference the loss of engine power checklist clean up items. Selecting alternate air in icing conditions and switching fuel tanks would have been the next steps on the engine loss checklist had the loss of power persisted. Alternate air was not selected as engine power was restored with mixture full rich and there was negative icing on aircraft or windscreen for the entire flight. In hindsight; alternate air may have resolved the fuel flow issue and prevented subsequent losses of engine power in flight. Contributing Factor: The repeated GPS interference and loss of satellite navigation in and around ZZZ resulted in an unnecessary complication of the divert procedure. Two repeated prior ATC notifications over the past year over the radio did not result in the resolution of this issue. Aircraft GTN750 was tested and certified for IFR flight since these notifications. A GPS approach or at a minimum vertical navigation with terrain avoidance would have been preferable to dependence on ATC and flying in marginal VFR conditions with visibility reduced by snow; increasing the safety margin of this divert. ATC did a great job filling in the gap!