Hi. I have 2002 Silverado 1500. 4.3 V6 4L60E trans. 131,000 miles.
When the trans shifts into 4th at 40mph, it feels and sounds like it is lugging. The truck is sluggish and I have to press the gas pedal down a lot more than normal to get it to accelerate and it shifts into like a passing gear.
Engine doesn't seem to have a misfire. Have tuned it up and actually had to replace a bad distributor. No codes are showing.
trans seems to shift ok except after reaching operating temp the 1-2 shift is very hard.
Along with the lugging , there is a vibration as well starts around 25 and stays but lessens after 55mph.
Scratching my head LOL. Any ides?