I have a 1995 S10 blazer 4wd, 4.3L automatic. The blazer is running rough when driven at low rpm's. I'm going to start from the very beginning. About a year ago my blazer was running rough and dying whenever I came to a stop. That problem went away after a few days. A short while after it lost quite a bit of power. I would have problems driving it cold, the car would either die when I gave it gas or it wouldn't rev past 2 or 3 grand until the engine warmed up. I let it sit at my parents for about 2 weeks before trying to diagnose it. On the drive home the car started miss-firing horribly and the car was shaking while I drove it. Once I got it home it sat in my garage for a few months so I could save some cash to fix it. What I initially thought the problem was was the fuel injectors, so I ended up replacing the spider assembly, fuel pressure regulator, nut kit, O2 sensors, cap rotor, plugs, wires and all the fluids. After everything was replaced the car started up and sounded fine at idle, when it was under load the rpm's would jump a little around 35-40 mph then again around 65-70 mph. This lasted for a few days then went away. Once it went away I thought everything was ok and decided to be immature and do some donuts in the dirt. Right after that the car started running rough again (all the way from idle to being under load) and the SES light came on. On the drive home the SES light was flashing. I got the car home and plugged in a OBD 2 reader but it kept saying error and to check the connection. I then tried it in a different car and it worked fine. I got online and saw someone said you need a obd 1&2 reader for my blazer, went to sears and bought one and got the same results. After that I popped the hood and my distributor cap was melted were the ignition coil plugs in. At this point I decided this all had to be ignition problems. I changed the ignition coil and at the initial start up it idled fine but when I gave it some gas it wouldn't rev past 3 grand until it warmed up. Once the engine warmed up it idled fine, when I put the pedal to floor it ran fine but at low rpm's it still misfiring slightly. At this point I'm not sure what the issue is, the SES light is still on but don't know why I can't read it. Not sure if it's just a knock sensor, the ignition module, the IAC or something else. Is there a possibility that the computer is bad and that's also why it won't read the codes? I know this is a very long post and if you read this thank you in advance for all your help!!!

 

First, check the cigarette lighter fuse. It powers the DLC.

Next, I would run through a fuel pressure test. Your symptoms sound very much like a fuel issue and a fuel pressure/leak-down test is cheap and easy to do.

If the fuel pressure checks out within spec, then the ignition system is the next logical focal point. Mist the wires down with water while the engine is running to check for spark leaks. A flashing CEL is due to a misfire condition.

Your '95 could be OBD1.5 or OBD2. I doubt it is OBD1 as I do not think the CEL will flash for a misfire code. Your reader needs to be compatible with the OBD1.5 setup which is not fully OBD1 nor OBD2, but a mix-mash of both.