A few weeks ago my 2000 Blazer started losing some acceleration and top speed. A little at first, then the problem got worse. I reached a point where I couldn't go over 40 mph on a straightaway and could not maintain any speed uphill. The truck would buck and jerk at various speeds. I did some research, cleaned the IAC, and the problems either went away entirely or improved significantly. I didn't have carb cleaner so I used a little carefully placed water and a toothbrush.

A week later the problems started creeping back. I planned to replace the IAC to see if that helped. Yesterday on my way to town the truck suddenly dropped speed to 30 mph on the expressway, bucked and jerked. I managed to get to an exit and get to a parking lot, but by then I could smell something burning. Had to have it towed that night.

Today I took out the IAC and cleaned that and the throttle body with sensor-safe carb cleaner. Fired up okay, wouldn't go over 30 mph, started bucking. Once it cools down I'm going to replace the IAC and see if that helps. If that isn't the fix what else might I be looking at? It sounds like it's sucking air, but I'm not sure where from at this point.

 

You need to get a scanner and see if you have any codes before going any further. A parts store can do this if you don’t have the tool.

George

 

Problem is I can't get it to a parts store unless I have it towed.

 

Look for broken or disconnected vacuum lines. To a point it will cause the problems you are having and explain the noise.

 

Thank you. I've checked all of the ones I can see and I sprayed break cleaner at the engine while it's running and couldn't see it getting pulled and no change in engine sound.

Any recommendations?

 

Basic code scanning capability is pretty inexpensive ($20-40):

Used/new code reader off ebay

New code reader off of Amazon

Bluetooth dongle and phone/tablet apps


George

 

Even tho i agree with somehow reading codes the vacuum line that is easly missed is the vacuum reserve ball that's usually mounted inside the drivers side fender at about the master cylinder.

 

I had heard something about that, but when I went to check there was no way I could see to access it. I found a few posts saying to remove the bolts on the ABS and fuse relay box to get room and do it by feel, so I'll try that this evening.

Update: replaced IAC, TPS, and MAF, issue persists though the symptoms are improving.

 

Congratulations! You have blown more bucks than a scanner advised by George. Keep on replacing and posting while we bring coke and popcorn for the show.

 

Dude, full returns accepted within 30 days of purchase. But feel free to eat your popcorn and contribute nothing to the thread.