I have a Volvo Penta 5.7 GXI - H&SX-A1.60, Engine number 4012195218E with stern drive in a Doral 21 Seaquest with few problems that may be related. 1st over the last couple of weeks the engine has started to stall out easily when decreasing the throttle to idle unless I take great care and decrease the throttle slowly, (the idle is steady at ~700 rpm after starting or slowly dethrottling). Today a more serious problem developed when the engine became hard to start (much cranking required) and then developed a problem where the engine did not respond to the throttle being increased but instead started chugging and sounding like it was about to stall at increased throttle (idle was still fine though), eventually after say 20-30 seconds with high throttle applied the engine would rev up and work really well so long as the revs were kept above the 1500-2000 range. Finally the engine did stall out and I was not able to restart. During all of this the engine has performed really well (normal) at revs above the 1500-2000 range.
Any ideas on what to check 1st?
Any ideas on what to check 1st?