Please Help! Rough Idle Stall

Hi have 93 blazer K1500 has about 226k it has a rough idle and acts like it wants to stall out if I put it in gear with out it running for like 5 mins or so then it'll really want to stall out unless I get on the gas.. Hears a list of stuff I have replaced not cause I thought its what it needed but some were codes some I knew needed to be replaced. Knock sensor, iac valve, fuel relay, icm, dist cap and rotor, plugs and wires, therm sensor, thermostat, therm switch, fuel filter, fuel pump. Also my temp gauge doesn't move at all only time is when I first start it it'll go up and back down and won't move same with speedometer. When the truck is idling the rpm will be between 400 and 1200 rpm but will fluctuate constantly till the engine smooths out timing was set correctly to 0 also.. I'm lost with options please help me.

Get it scanned and look at the coolant temp sensor is telling the ecm. They had a high failure rate causing poor cold and/ or hot performance. Egr sticking open is also a possibility.

Egr is good temp is also good I just checked them. Also idk if this help but when you disconnect the harness to set the timing the blazer runs perfect when you plug it back in it idles rough wants to stall. Idk if that helps any..

Temp on the gauge isn't necessarily what the ECU is reading, that is why max said to get it scanned to see what the ECU is seeing.

As I said I have checked fhat.. But doesn't explain when I disconnect the timing bypass wire it runs perfect but when I connect it it runs rough.. Next step is to say screw pull the engine and rebuild the damn thing

You didn't specify. You just said temp is good.

Rebuilding the engine won't do any good if it is something electrical causing your issues.

Doesn't help the guy before me messed with the wiring its a damn mess I talked to my buddy he kinda has me sold on junking the tbi and switching to carb this blazer is a damn headache it just baffles me that if I unplug the advance it'll run fine plug it back in runs like shit for about 5 mins then it'll idle fine till I shut it off once i,start it again same process again.

I think the advance will change fuel settings. The throttle body gets dirty like a carburetor. http://www.rockauto.com/ sells a rebuild kit and a fuel pump pressure regulator for these throttle bodies. Sometimes the injectors get dirty. http://www.alldatadiy.com/ get a years subscription they have wiring diagrams.
http://www.ebay.com/itm/302437817808/www.ebay.com/ (http://www.automotiveforums.com/vbulletin/www.ebay.com/)
Pull the distributor cap and place engine on TDC or zero degrees use white out and mark rotor and side of distributor, rotate engine about 90 degrees counter clockwise. Then rotate clockwise to mark on distributor if you have over 10 degrees difference you need a new two piece timing chain. They use a fibre gear and they wear.
Use a can of starting fluid when the idle changes sprat some in the throttle body to make the mixture more rich if it runs fine you either have an intake leak or a partially plugged injector or a dirty throttle body. Follow Tech 11 guidance to find leaking intake or vacuum leaks. Using a carb,will probably require a new harness and ECU for carb,or a distributor with a vacuum advance and coil built in.

Have you checked for vac leaks? Spray carb cleaner, systematically around the engine to check for a change in idle........