i just bought a 99 ram 1500 with the 5.2L v8. when you are driving it feels like the engine miss-fires and chugs every once in a while, like when going from a dead stop or when the truck shifts into overdrive and drops the rpm's down. it only does this a little bit but i know i need to take care of it right away. i only paid $1800 for it and this is the only problem it has, the owner didn't want to deal with it so they decided to just sell it. any ideas where i should start looking for the problem? the owner said they changed the plugs and wires but it didn't stop it from happening.

 

Plenum gasket, or clogged cat

 

this is probably a dumb question but what would be the best way to check either one of those without tearing apart to much stuff? should i check anything else first, like maybe have a tune up done? someone told me it might be the distributor or the coil.