about 6 months ago I started having some issues with 1999 Blazer. when you start it up it idles fine, when you put it in gear (normally reverse) and you start to backup its real sluggish, like it loading up on fuel, no black smoke or anything, if you put it in neutral and rev it a little it fine when you put it back in gear it like I have lack of power, if you baby it along then in 200 feet it clear out and runs fine. then if you let it sit for a hour or two it does it again or it will not do it for a few day, then it back again.

actions taken so far.cleaned air filter (some trash in it but not much)

• done the SeaFoam trip
• replaced all vacuum lines (they were crumbing)
• run fuel injector cleaner through it
• cleaned the MAF with contact cleaner
• fuel pump was replace 3 years ago
• fuel filter replace 3 months ago
• replace filler cap

I am running out of ideas, another symptom that might be related to it, it surges running down the hwy with the AC on (it didn't do this in the past)


other work done to it is about a year ago new transmission installed,

3 months ago

• new brakes
• shocks
• half shafts (both sides)
• front wheel bearings (both sides)
• idler arm
• front end alignment
• door hing pins and bushings
• left side front differential seal
• stabilizer bushing (front)

 

things I don't think is related to this issue, but might be are fuel gauge is possessed (bounces all the time or goes to empty or full all the time) alternator wines, doughnut gasket leaks with it cold on right side. I have also replaced the radiator and water pump in the last 2 month also. 6 month ago replaced front drive-shaft.

there is not codes in the computer and no check engine light lit