i have a 92 jimmy 4.3 vortec went to work and started running rough when i got to work came home still running rough replaced spark plugs ,wires , cap, buttons, o2 sensor, both trottle relays , water sensor ,fpr sensor ,fuel filter, map sensor,tps fuel pump getting 62 psi at the engine sparks plugs getting blue spark, took off the cat and put a new muffler on starts sounds like its missing rough idle still checked to egr valve thats fine put a code reader on and says things r fine passenger side manifold is warm the driver side manifold is hot replaced those things one at a time when one thing didn't work tried something else vacuum is about 5 need help please

 

5 pounds of vaccum does not sound right for these engines. What is your compression in all cylinders? You could have a bad air leak in your intake manifold, maybe replace your intake manifold gasket, uper, and lower. If your compression is low id check for blown head gasket. Five psi. of vaccum is way low. Any check engine codes?

 

took the plemon off again and this time found gas in the inside i was told thats not good so i got the fuel injector going to see how that works today if its still missing we'll check the manifold and the vacuum again code that come up 12 and thats normal but u can hear its not normal

 

Did you ever find out what the problem was?

 

replaced the spiderwith anew one still had problems got tried of it and took it to a garage they said the spider was bad took it back got a new one blown out the return line with air still not right something still not there

 

find the problem broken valve spring

 

Yikes! That would do it though! Thanks for the followup!!