Ok,this has me beaten. I drove my blazer into the garage and removed the plugs,took the coil to dist wire off and proceeded to check compression on all cylinders. the next day I replaced the plugs back into the same cylinders they came out off, installed the coil to dist wire and the engine would not crank up(it would turn over but wont run and every now again it rumbles like its flooded or out of time).
So i doubled check the plug wires,looked for any vacuum lines or any electric plugs that might have came unplug,nothing.. i placed a in-line spark tester on #3 cylinder,I have good spark. first thing I thought was it was flooded,but it has been 2 days and still acts the same. I moved on to fuel, I can hear the fuel pump but checked all the fuses anyway. all good,so i removed the fuel line from the tbi and spun it over and have fuel,installed a noid light to check pulse on injectors,good pulse signal. checked the injectors and both are good. now confused i started checking everything,coil tested good on all 3 tests,installed 4 in-line tester on #1,3,5,7 cylinders all have good spark, did the same on other side and all were good as well.i tripled checked the plugs for firing order all are good. i thought well maybe something is wrong with the plugs so i removed a plug installed the plug wire and spun the engine and i have spark. i even tried putting some gas in the tbi to see if i could get to crank and same as before, nothing...So now i am out of ideas,if anyone has a different train of thought i am all ears....

 

I would check to make sure the timing has not jumped. Bring #1 cylinder to TDC and verify that the rotor is pointing to the number 1 plug. I would double check to make sure that the distributer hold down bolt is not loose and that the distributer did not rotate. I had a car where I changed the oil in my driveway and would not re-start. Turned out that the timing chain jumped time. Strange things sometimes happens. You have fuel, spark so the next thing I would check would be timing.