Hi. I car has not start for awhile because I haven't have a chance to look at it but last week I work it for the weekend. The reason it didn't start because it doesn't have any spark and the ECM has 3 fried transistor so I put another ECM from the 1995 CIVIC LX. By the way, the car that has problem is the 1993 CIVIC DX. The car start fine but it doesn't idle. Look like it kept on adding gas and decreasing, what I mean it's the rpm go up & down from 800 to 2000.

I think the problem is because I didnd't install the intake manifold gasket so I went out and bought the intake manifold gasket and not the car doesn't start anymore.

When I look at some of the coolant, one hose is clogged and can't get through and looks like it got some sort of sand in there. Oh, I forgot to tell you guys that the first time I start the car there isn't any coolant in there but I added some in there and I think that clogged pipe doesn't let the coolant enter the engine and at one point the temperate went almost to the "H" so I shut it down and turn on the car to ON not start it's still at "H". I done for the day and trying to start it again and this time it wouldn't start.

Maybe I have a blown piston or head gasket because the car got so hot ?

Please advice.

Cracked or warped head. Warped or cracked intake. Intake seal not seated. When a car fluctuates at idle to the extreme you say yours is it sounds like oxy sensor is telling ecm to adjust oxy intake or restrict it. It sounds like a top end tear down and ecm check to me.

... and check that clog in the radiator too.

I cut the hose that connect from the head to connection below it (not sure what you call it), the one that has another connector hose from the bottom of the radiator connect to it and also have the connection from the head connect to it. What do you call that thing? Anyway, it clogged right there and it rusted so when I removed the hose it just break of the connection therefore I can't connect the hose back on after I unclogged it. I have to order another one but I don't know what it called. I have checked for another head and I fouund one on Craigslist that is for sell but it's a VTEC head with solenoid. I don't think that is an issue right ? I heard that the VTEC head can also be bolt on the non vtec block, it called "mini swap" but if I don't want the VTEC feature so I don't have to rewiring or have to change to VTEC ECU or anything, right ?

How can the head be cracked ? If it cracked then it wouldn't start in the first place. You mean it cracked after I started the engine ? What do you mean intake seal not seated ? You mean the bolts are not tight and it let airs out from there ?
I'm to learn about cars so questions always a good way to start and then lay my hands on it... I mean working on the engine.

After I removed the hoses I used the water hose let water run into the system and flushed all the coolant out. At first I see the water is sort of brown at the connection where it got clogged but after a minute the water is clear. Now, no more coolant in it. I need to know what's going on what need to be replace before I put the coolant back in and crank the car again.

You need to buy a new hose and you may have to replace the radiator and the thermostat and other things pertaining to the radiator.
As rcremsing said you most likely need to tear down and rebuild the whole top end
Hopefully you did not do any motor damage.