VP 3.0L won't start after warm

[Glastron175]

My 3.0L (2000 model) starts easily cold. After warm-up I kill the engine, then it won't start. Also, when running it bogs down at about 3400RPM, but smooths out again about 3600RPM and runs fine on up to 5000RPM. Same thing on coming down. Bogs at about 3500RPM then smooths out again at about 3200RPM and runs fine on down to idle. Perhaps related is the temperature. It never gets over 150 degrees. I think it should be 160 for this engine. Any idea if these are related problems or have any suggestions?