I'm a bit stumped on this Blazer. When I bought it I replace the injector and nut kit and did a compelete tune-up using mostly AC Delco parts, plugs, wires, cap, rotor, fuel filter (Fram), both temp sending units (Borg Warner), air filter (the coated Fram one).

Considering it barley ran when I bought it, knowing it needed the injector or nut kit replaced, after replacement, it seemed to run like a dream. After aquiring the 95 Blazer, I noticed how much smoother that engine runs at idle and just off idle than my 93. What is odd with the 93 is that about 40% of the time, it runs smooth at off and there is no stumble just off idle. However, it is the 60% of the time that really is starting to irritate me.

It gets particularly bad when I try to accelerate slowly and the engine feels like it is either starving for fuel and wants me to depress the accelerator further or feels like it is about to fall flat on its face.

Gas mileage has been terrible as of late, in the 12 - 13 MPG range. I am going to remvoe the upper plenum this weekend to see if the nut kit or injector is leaking, but beyond that, I am stumped.

Here are some photos of my injector and nut kit replacement from when I bought this Blazer.

 

Well, apparently my off idle hisitation is tied tot he EGR vavle, and possibly my rougher than normal idle. I had my GM certified mechanic freind drive it and as soon as he felt the off idle hesitation he said it was the EGR valve and also felt the idle was caused by the pintle not seating all the way.

I took the EGR vavle off this evening and checked the pintle movement, it moved in and out free and smooth. There was still no chunks within the EGR or the opening in the intakes, they were black, but otherwise clean and debris free. I reassembled the EGR valve and the vehicle is back to idling like normal and there is no hesitation. It is running much like it did when I originally replaced the Injector and nut kits, so I guess I'll see if the engine stays running smooth or starts to act up again.

 

If it does act up. soak that sucker with some brake parts cleaner. Ten wait a bit and dump the cleaner out. I had to replace my gasket cause it was crushed.

 

Clean the IAC and Throttle body with carb cleaner...helped me a bunch 'cause they were gunked up with carbon...

 

As per my friends suggested diagnostics, I disconnected the EGR valve's wire harness. He said it would not affect the idle (since he suspects it is not fully seating), but if it was the EGR valve, with it disconnected, the off idle hesitation would go away. So far he seems to be right on. Naturally the CE light is on, but the engine is running smooth and hesitation free during slow speed acceleration. I've often thought I needed to replace my front brake pads, after he drove it, he said his suspicions of the EGR valve increased due to the rock hard brake pedal. Apparently with the EGR valve hanging, it doesn't retain adequate vacuum for the brake booster.

I'm going to leave it disconnected for a few days and see how it goes. I'll probably give it a shot at soaking it in brake fluid to see if it could possibly help, otherwise it appears it will need to be replaced.

As an aside, I'm rebuilding a 4.3 out of a 98 Jimmy for my 97 Bravada. I pulled the EGR valve from the 98 4.3 engine and compared to it, the one on my 93 looks like new. I may install it on the 93, the wire harness is not compatible, but if the newer EGR valve is seating correctly, it would correct my slightly rough idle if the original EGR valve isn't seating properly.