Hoping to find some good news, but I've read a lot of the threads on here and not sure what's related and what's not.
My 88 Chevy truck needs tranny and figured while I'm doing that I'd fix a few other issues as well.
Bought this 97 blazer couple months ago as a temporary vehicle. Good runner, and comfortable, decent pickup, nice. Starting to really like this truck, might keep it around. Even used it for family trip in September, 4 hours each way, fit 4 adults comfortably, fully loaded with our stuff for long weekend and even a package strapped on the roofrack. Almost 18mpg. Not bad for 22 year old, 160k, $1200.
Now it's all downhill.
Had an issue with the key being stuck in ignition and truck not wanting to take off in first gear. Changed ignition lock. Solved that one (mid October). Issue returned about 2-3 weeks ago, since I'm only using it now for back and forth to work, I've been shifting it to first manually at stops. Can't seem to find an answer as to why it re-occurres.
Monday, suddenly runs like s#$t. Especially at idle, better at driving/highway but lacking in power and acceleration. Friend at work who's more into newer stuff than I am, says this year has egr valve that goes bad. Replaced egr valve, little better, not much. Ran over to O'Reilly and plugged in scanner. P0802, missfire cylinder 2, and bad O2 sensors. I do not have a check engine light. It does not even light up on turning the key to on but not starting the truck. So had no pre-warning of any bad sensors. As for the rough running and supposed bad egr, they occurred with no warning at all.
As I said, I've read quite a few threads on this forum, and it appears these 4.3 motors are quite particular. Is there somewhere I should start looking for the missfire? Spark plug change, complete tune-up? Don't want to start throwing money at it where it might not be necessary. Plug wires, cap, all look very good, guy I bought it from said this was all done in the spring not long before I bought it. But reading some of these posts on here, if he used cheaper "house" brands, that could be a problem. I don't have access to all scanning tools and pressure testing equipment in my garage.
Am I at the point of starting with the $180 complete scan to see what a shop has to tell me? Plus whatever needs to be replaced. Like I said it was only a $1200 temporary vehicle, but I did want to at least get me through the winter, maybe longer. Kinda like it, I had another one a few years back and liked it too. Or maybe the other guy just kept using cheap replacement parts.
Don't want to throw a lot of money at it.

Any help would be greatly appreciated

 

Don't waste your money with a $180 scan - a machine hooked up to your car without expert further diagnosis isn't really going to tell you anything more than you already know. Get your own scanner. For a 1997 Blazer, if you have an Android cell phone get Dash Command (Google Play, $10 + $10 subscription for your Vehicle PIDs) and the BAFX Bluetooth OBD2 dongle (Amazon, $25).

I think the P0802 is Probably really a P0302 (which is the misfire on cylinder 2). Lots of O2 sensors replaced needlessly. Probably the misfire is causing the O2 sensors to read out of range. Don't want to run around with a misfire for long, as this ruins the catalytic converters and will cause them to need replacement.

So what to do for now? Back to basics. Identify for certain which cylinder is misfiring (sounds like it is missing all the time). Pull the plug wire out of the distributor cap for cylinder #2 (front passenger side) and start engine. If it runs the same as when it is hooked up, you have definitively identified the cylinder that is misfiring. If not, you will need to do the same for the other 5 cylinders until you find the one that is misfiring. Misfire ID by the PCM sometimes gets cylinders confused. Once you have found the misfiring cylinder, you will need to remove the spark plug and inspect it - also check the spark plug wire with an ohm meter and inspect the inside of distributor cap/rotor for carbon tracking. If those are OK - do a compression test on that cylinder. If all that is OK, test fuel pressure per sticky at the top of the second gen forum. Report your findings and we will help.