94 suburban cranking over really slow seems like its not getting enough power to start

Easiest thing first, check to see if your battery is still good. Any automotive shop should check it for free

what he said. Did you check the battery? Even a new one can be bad. I work at a parts store, i know

There is also the posibility that your intake gasket is leaking coolant and filling the cylinders. When this happens it will do as you described and it don't mater how good your battery or starter is. Through process of elimination that most often can be done at no cost you can diagnos most problems. As mentioned above many things can be taken to a auto part store to be checked. One most over looked thing is the acctual condition of the positive battery cable. If in the past you have had to clean the connections, especialy if they had heavy corrosion that sometimes the breakdown can occure where you cant see even after cleaning them. Corrosion can form arround the copper wire in the terminal itself reducing the continuity. Next be sure that you have a good ground. After those preliminay checks move to the battery. Remove the battery and have it load tested. This is commonly a free service at a parts store. Do this at a reputable store and beware that you can be tricked into buying a part that is not bad. If you are told it is bad and you purchase a new one and it still does not fix your problem is not proof that they sold you a part that you did not need. Most times they will let you witness the test so don't be a jerk just ask. If your problem still exists after those basic test move to the starter. This is another part that you can take to the parts store to check out commonly for free. As mentioned before ask nicely to witness the check as this too can be one of those tricked into buying another that still won't fix your problem but does not prove that you did not need it. If you still have not found the source of the problem by now, The next step is to be sure that the issue is not from the engine itself. Remove all spark plugs and prop the throttle plate open on the carburator or TBI. Make sure that if you have a manual transmission that it is in nutral with the parking brake set. Using a socket and ratchet rotate the engine by hand using the ratchet in the tightening setting. Wtih the spark plugs removed, throtle proped open and transmission in nuetral, you should be able to rotate the engine with only mild resistance. If there is a strong resistance to turning it mostlikly points to a internal problem that will require major repair. If it moves with only mild resistance, continue to rotate for several complete revelutions. During this time watch for liquids to come out of the spark plug locations. If liquids come out, then it is likely that you have a leaking gasket. Liquids do not compress and make it hard on the engine to turn. All of the above mentioned tasks can be done at no cost to you other than your time and gas money driving to the parts store. If at this point you have ruled out all of the above, You have a demond inside your vehicle and should take it to a repair shop to have an excercisom performed. I hope this was helpful.