Hard starting and stumbling after started
 

Hello i'm new to the forum, i'm a shade mechanic sorta but I have a problem. I'm hoping that the collective minds from this forum can help me out. I have a 98 3.2 rodeo with new heads and a bunch of new parts, I even put new cat. converters on it. About 3 weeks ago it became hard to start, I would have to pump the gas pedal (which makes no sense). When it does start it stumbles and acts like its flooding then it will clear out. After it clears out it idles smooth and runs great. After it is run up to normal operating temp it will start just fine, its only after it sets over 30 mins that it becomes hard to start. I have replaced the fuel pressure regulator and checked the pressure (45 psi key on engine off, 36 engine running idle). I'm not for sure even where to start, I've heard that sometimes the fuel pump neck will crack and cause this. I filled the tank and it still does it. The heads were put on back in august so I don't think there is anything wrong with them, I followed the manual step by step. I did notice yesterday while trying to start it I heard a bubbling sound coming from the engine compartment (after I had shut the key off, the engine was not running at this time). I can smell antifreeze on the driver side of the engine not sure if this is related or not. The engine does not get hot, it just barley makes it half way up the gauge. I have noticed that sometimes when its hard to start when it you drive it, its shifts harder. Any help would be greatly appreciated. Thanks