You said it would start again after about 5 or 10 minutes then go a short distance, then later on said it would start about an hour later and run for about 15 minutes, you need to also check for spark after it dies when it doesn't want to crank, you may have a bad ignition module or crank sensor maybe, Does your vehicle has distributor or coil packs? You said it seems to run fine when it does so it may not be a clogged cat. Does it give you trouble when trying to crank it those 5/10 minutes later or hour later or does it fire right up after it's cooled down?