i have noticed when it shifts into 3rd gear around 35 mph i get a loud thud
and then if i lightly keep light pressure on the gas pedal around 25 mph
i hear soemthing that sounds like popcorn popping it appears to be coming from the exhaust
and if i accelerate it goes away.
any suggestions/comments

truck has 67,000 miles on it

 

my 01 does that thud when it shifts.. someone mentioned to me to change the gear ratio in the rear end.. the popping sound.. started like that on my 99.. then it went fast.. plenum gasket.

 

ok thanks for the information
i am gonna have to take a look down the TB for oil
will do that in like 10 minutes after i eat
i will post whatever i find out

 

well i see a very light film of oil when i look in the TB
i do not see a pool of oil anywhere
i also checked the IAC and the MAP sensors when i unhooked the IAC it ran just fine
after the initial rpm drop for like a second then i unhooked the MAP sensor and it died
but i could start it up after that without hooking the MAP sensor back up
while i was there i also checked the wire routes and they all seemed to be ok
so now that my cat is gutted and all of those things checked any ideas

the truck is all stock except for the 3 inch lift

all input would be appecitated and most certainly used

thanks guys