97 blazer misfire
 

ok so about a week ago i started my truck it idled fine and ran fine in drive while at an idle but as soon as i gave it some gas it started sputtering and missing followed by a check engine light. when i let off its fine when im on it it sputters but when the engine gets to operating temperature it is miraculously fine. it does this every time i drive the truck. I pulled a p0304, p0440(it was there twice), and a p1406...any body know whats going on

P0304 - Cylinder #4 Misfire (search term "P0300")
P0440 - Evaporative Emission Control System
P1406 - EGR System Pintle Position - Most likely caused by carbon prohibiting the valve from operating properly.

after doing some reading i decided i went ahead and cleaned my egr, maf, and throttle body. before my truck idled at about 600 rpm now it is idling at 1000 rpm and is rougher and when driving when i let off the gas the rpms will jump about a 100 from where they where when i let off and it will hang the for about 10 seconds and then start to drop very slowly...anybody have any ideas why this is happening

Sounds like you now have opened up a vacuum leak somewhere during your repairs.

Have you done anything to address the P0440 code?

on the p0440 i suspected the gas gap as the oring looked worn down so i replaced the cap and cleared the code so far so good...im gonna check for a vaccum leak tommrow

well all that and my problem is still not fixed still got the miss when engine is cold...starting to get a bit frustrated with it