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I have a 2000 Astro Van 4.3L and after starting and driving first thing in the morning it hesitates and stumbles, like it’s cutting out. If I accelerate I don’t feel it, but when I return to normal driving it returns until it warms up, then it responds normal. This happens from a dead stop on acceleration to about 35 mph. I have changed the fuel filter so far. Any help would be greatly appreciated.
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If the problem is not present after the vehicle has warmed up, you may have a gasket leaking (vacuum leak) seeing as metal expands once warmed up.
Keep us posted.
I would check the oxygen sensors for proper function and the exhaust system to make sure there is no restriction.
I’ve heard that these 4.3 engines tend to leak at the intake manifold too, but I think I would notice it while it idles.
It depends on how severe the leak is.
You would need to look at fuel trim numbers.
Id also do a cooling system pressure test as the lower intakes on those motors can be known to leak.
Start with any check engine lights you might have. The above videos will get you started and here are a few that may also help.
Vacuum leaks
Re Performance Problems
Don’t really know what happened, but one day I decided to unplug the connector to the air flow meter and plug it back in, then tapped on the meter with a screwdriver handle, and it’s been running good ever since.
Thanks guys for the input.
Thanks very much for the update. In the future if you have the issue again you may want to clean or replace the MAF sensor. Keep us posted if things change.
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