87 Suzuki samurai, engine "misses" throughout driving speed range and hesitates/stumbles during acceleration. Stumbles even while trying to rev it in neutral.
-engine timing is correct, tho idle is high probably due to a weak return spring on the throttle
-engine was fully rebuilt in March 2016 so do not suspect anything internal
-I have replaced all vacuum lines
-replaced fuel filter
-checked fuel delivery to carb from pump, appears adequate
-all spark plugs are clean
-replaced all plug wires and coil wire
-replaced gasket between carburetor and manifold, ensured a nice tight seal
-checked function of the mixture control valve by following directions in my manual. passes the test. (Disconnecting the small hose from the valve, reconnecting it while simultaneously holding a piece of paper close to the under side of the valve. The paper was drawn up to the valve like the book indicated and the motor ran rough while performing the check as the book indicated.)
-checked the EGR valve by touching the diaphragm while motor was cool and then while it was warmed up, revving it slightly at both temps, diaphragm didn't appear to move during either check. Book indicates it should at warm temps, but I don't think mine did. A mechanic told me these rarely get stuck open, so I ruled out the EGR by disconnecting it and performance was still bad. Unless it truly is stuck open...?
- I do have a crack in my exhaust pipe in the last 1/3 of the pipe. I feel this crack is far enough back that it couldn't be the culprit. Please correct me if I'm wrong!

At this point I have troubleshot everything I know to do and am stumped. Where else might my problem lie? Do I need to rebuild my carburetor?

Any insight would be greatly appreciated!! Thanks a lot!

Katie, zukchik

My son had a similar problem with his SJ410, it was the rubber line between fuel line and tank.  It was cracked from old age.  You might want to check it out.

Did the engine hesitate and miss like this before you had it rebuilt? If not, then something wasn't put back together/on correctly, when the engine was reassembled/reinstalled, more than likely.
New spark plug wires can be bad out of the box. Do you have the old wires around? Did it run fine with them on it? If so, then swap one of the old wires for one of the new wires and see if it runs better...do this for all 4 wires, until you have all 4 old wires back on the engine.
Are you sure you have the plug wires on the correct cylinders? If you have 2 on the wrong cylinders, then it will run poorly (probably wouldn't even be driveable).
Another thing you could try, is to pull one plug wire off while the engine is running. The engine should run noticeably worse, when a plug wire is pulled off the spark plug. If it doesn't, then that plug wire, spark plug, ignition cap tower, or cylinder is where the issue is. If it runs worse, put that plug wire back on and pull another one....do this for all 4 and check the results.
I didn't see where you replaced the ignition cap and rotor. I'd recommend doing that too, if they haven't been replaced recently.
How high is the idle? A vacuum leak, or a line in the wrong place can cause high idle. A high idle after initial startup is normal, until the engine reaches operating temp. But after warmup, it should be right around 800rpms, with no electrical load (lights off, AC off, etc.).
Are the valves adjusted and adjusted correctly?
To check to see if the EGR valve diaphragm is stuck, you can push in on it, when the engine is off. It will probably push pretty hard, but if it moves, then it isn't stuck. I use both hands, 2 fingers, 180* apart, to push on it...ensures I am pushing evenly and makes it easier to push than just using one hand.
Are you sure your crank to cam and cam to distributor timing is correct? It is sometimes hard for people not familiar with these suzuki engines to get it set correctly. If the crank mark is at 12:00 and the cam mark is at 12:00, then the distributor rotor should be pointing to the cap tower that the spark plug wire that runs to spark plug #4 is connected to.

Might have been the cam wasn't aligned properly? Compression test would test for this. What do the spark plugs look like? Wet? Dry/white? Maybe the coil is crapping out and is not pushing enough voltage.

Thanks for the replies tho I still need help, things have gotten worse!. Firstly this is not a cam/valve/anyhing internal issue. the motor was rebuilt months ago, I have been driving it all over the country and I am just now having issues. To address and rule out ideas from members;
-spark plug wires are new and in the correct place
-spark plugs are clean
-brand new distributor, distributor cap, and rotor
-brand new coil
-fuel system is good to go

Now all of a sudden I am not getting any spark from my coil. Any coil for that matter, as I have swapped multiple.
*** I looked up a schematic for 86-89 samurais, it says I have have an ECM (engine control module) which is connected to the coil on the positive side. Could this be my problem? Regardless, does any one know how to test this thing? There is also a condenser on the positive side that I don't know how to test..  any further ideas about what my problem could be would be much appreciated! Please help!