is this a transmission issue?

[Pistons23]

my truck is a 2000 ford ranger xl w/ 2.5 4 banger backed by an auto trans. my problem is when the truck is cold. like first thing in the morning or after its sat and completely cooled down. when i put it in gear(reverse or drive) the engine bogs down and hten picks back up. it only bogs down for about 1-2 seconds. once the engine is warmed up the problem goes away. so i was thinking maybe its the transmission. i used penzoil mercon v when i drained the trans a few years ago. i thought it was the idle air control valve, but i just replaced it this morning and it didnt change. so that part is going back. now im begining to think its a transmission problem. any thoughts or insight into this problem?

 

[Jspafford]

How much does it bog down? If your truck is still cold and at a higher than normal idle, dropping it into gear will usually lower the RPM. It should not, however, drop it down any lower than a normal warm idle.

 

[Pistons23]

the rpms drop like its about to stall. a few days ago it actually did stall. i know the rpms are high when i first start it, then after about 30 secs it drops to a normal idle.