2001 Mazda B3000 Starting problem

I have a 2001 mazda b3000 with a 3.0 liter engine. Head gasket were replaced because of overheating. Heads were checked for warpage, and for possible valve damage and cracks. Heads were checked out fine. Installed using new head bolts, torque the heads in sequence and in three steps to factory specs. Also the rocker arms were also torqued down in two steps with using the factory specs. Never did the timing was touched and it also has a distributorless ignition. Coil pack, spark plugs, ignition wires, crank sensor, thermostat and gasket are all new. The engine turns over a little then binds, like if though something is jambed, then it will spin a little quicker, then again turns slowly as if something is jambed again. I'm at a lost at this point on what to do. Please help!