Calling for expert on Mazda B2000

This has been frustrating. I think I get this thing running well and it up and fools me again. Okay, the vehicle is a 1983 Mazda B2000. It has 234,000 miles. I have, so far, changed out all the emission hoses, the distributor car, rotor, wires, and plugs. I have removed the carborator and cleaned it, replacing some of the internal parts that came with the kit. The carborator is a two barrel Nikki; it is my understanding that this particular carb came on these pickups as standard. I have replaced the PVC valve. I have cleaned the afterburn valve and the EGR valve, they both seem to work right. I have increased the fuel efficiency from 20 mpg to 30 mpg. The pickup will start without first setting the choke by depressing the gas pedal. It will idle until it warms up, then it starts stuttering and will eventually die. I must pump the gas pedal to get it started again. Usually I will have to press the gas pedal to the floor and hold it there until the motor smooths out, at which time the rpm's are soaring; pretty hard on the ol' girl but that's what I have to do. When I start down the road, the motor bucks and snorts, puffing back up through the carborator and leaving black soot on the walls. The only way to get the motor running smoothly is to again press the gas pedal to the floor and leave it there until the rpm's get up high before shifting. I am thinking this may has much to do with the choke setup, but I am not sure; it may be several things. Anyone up for the challenge?

Reply to
jettaman8691
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I have replaced the fuel filter and the fuel pump, but not the fuel lines; they seem to be clear. The filter in the banjo connection was/is clean, or at least it appears so to me as I made my inspection. I did blow it out, but I will re-check it today just to make sure. I have not done a compression test, but will do so. The motor will start very easily when cold, but runs rougher, stuttering with short lunges, as it warms up. It is at that point that the motor pops back up into the carborator. I haven't characterized this action as backfiring because my experience of that is that backfiring is accompanied with a loud bang, but you may have something here with a bad intake valve. I am so very thankful that you have taken the time to analyze this for me. God bless you.

Reply to
jettaman8691

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