I will begin with this site is excellent would have loved to have run across you folks years ago. My Problem, mower starts instantly and only at full throttle and choke. Once running will die if choke is fully depressed. Can mow at a snails pace with no power at about 1/4 choke. Interesting part..Mower during snails pace operation will occassionally "cough" throw a lot of bluish white smoke and run full rpms and power...this never lasts longer than a few seconds. The Mower. MTD The Motor: 16HP Twin II Model 42A707 Type 1238 01 Code 9602125B Three screw fuel pump. Attempted fixes so far. Fuel pump rebuild kit..Very thouroughly cleaned carb drained all fuel. Rinsed tank (with fuel)..new fuel lines..new fuel filter...twice..first was cheapy with wire screen second time with bosch with paper element...and needle valve replaced. Inherited this from grandfather and even though it is not a classic or collectors mower it still holds value to me and is irreplaceable. Really want to get this thing going right. Thanks if you have advice of any kind.