93 dodge dakota transmission questions?

I own a 1993 Dodge Dakota 4x4 automatic with 165,000 miles. About a year ago I noticed my transmission was acting funny like at high speeds it wasn't shifting into the right gear or sound like it was in neutral because the RPMs went up. Anyway, I noticed when it was winter season that my transmission ran worse because it was very cold. Now that it is almost summer and it is hot outside my transmission is shifting 80% better. So now here is the odd part, the other day the temperature drop into the 30s and when I took my truck for a drive my transmission was acting up. When it is hot outside my transmission runs better and when it is cold my transmission shifts wrong.

.........>>> Also I hear a thunder rumble type sound coming from the front of the transmission whenever I let off the gas. Sometimes it feels like my gas pedal is soft at times then hard like when I push down on it.

So my question is how would the outside temperature affect my transmissions shifting?

.........>>> Also I hear a thunder rumble type sound coming from the front of the transmission

Torque Converter or fluid problem?

Thanks