Rough running at startup

I just recently bought a 1998 dodge ram 1500 with a 5.2ltr engine. The problem is when I start it cold and it runs fine and then it begins to run rich and rough while idling and you can hear excess air being drawn in from the throttlebody intake. I am told this is the air compensating for the excess fuel being used. After about a minute or so it smooths out the hissing goes away and and runs fine. I have done several things to try to diagnose/fix this such as replace coolant temp sensor, cleaned the idle air sensor, new plugs,wires and air filter. I have checked for codes and there are none and the fuel pressure is good. Any ideas?

How cold are we talking about outside when you start it?

Thanks for replying fredjacksonsan

I bought the truck in October so the temperature outside has varied, say plus 10 degrees to minus 20 degrees which is typical for Southern Ontario weather this time of year.

What do you mean by your second statement?

That's my signature, it goes on every post automatically. You can set one up also, go to the "User CP" at the top of the page here, and look around in there. Your avatar is the picture that appears in the left margin.

Actual meaning of the statement; People always wait until the last minute to get something done that takes a week or two, then complain when it can't be done.

I'd say with it that cold, that one minute for everything to warm up and the computer to catch up with all the cold sensors, isn't too bad. Especially if it runs fine otherwise.

That's the choke. It's cold outside.

Thanks for responding
Lately it seems to have gotten worse. I got into the truck and started it when its hot it did the same thing but only if I get into the truck and dont go anywhere just let it idle. If I get in and leave right away when its hot and depress the accelerator, the engine looses power and kinda boggs down. Its like it was being flodded or something and it backfires in the exhaust manifold. As soon as I lifted my foot off the acccelerator it levels out. Could it be a gas problem like the fuel pump,regulator or filter?

Thanks for responding bleeddodge

Could the choke be the problem if its hot as well?

So it still does this even when it's hot? That shouldn't be.

Is the check engine light on?

Hi bleeddodge

There are no codes in the computer and the check engine light has not come on. This is why I think it is a fuel problem.

Turned out it was 2 fold 1st my fuel pump was goin g bad and sucking to much air second my CO2 sensor in front on my catalytic converter was going bad. CO2 sensor did not set of my check engine light at first.

Over all truck need tune up plugs, plug wires, etc.... along with the above. but once I fixed the 2 above item truck ran like scoulded dog.

Sounds good.

Thanks for responding Bzechar

I believe quite frankly that it could be a fuel pump or regulator problem. Did your check engine light come on for the bad 02 sensor? If so how long did it take to do so? I dont know where you live but in Ontario Canada where I live we have to have our vechicles emissions tested every two years. My truck was done just before I bought it last October and the technician said the 02 sensors seemed ok. I guess they can tell to a certain extent by the test results.

There's emissions testing in Ontario?

Hello Bleeddodge

Yes there is. The testing has been in effect for some years now. Do you have it where you are?

Not here in Manitoba, to my knowledge. Myself and everyone I know hasn't had to do it.