when driving the engine will race but the van does not speed up,,also happens on start ups...of course it is an intermittin problem...any thoughts ..throttle postion sensor?..thx all....

edit:4 banger

 

Is the transmission slipping?

 

well i wouldnt say it was slipping..but it has no power when pulling out if you have to step on it, and at around 40mph it bucks and jerks when trying to shift it has 110,000 on it nevre had problem , just oil changes and coolant ever done....i did change the sensor in the cat and new plugs 1000 miles ago

 

i dont drive the van that much, and when i just drove it ...yes the tranny is slipping

 

Check the tranny fluid,if it has a dark appearance or smells burnt you are going to need a rebuild.Make sure it's actually slipping and not just stuck in one gear.The latter problem could be a $20 speed sensor.