started having problems at 82k miles with 1999 dodge dak 4wd 3.9 v6. engine has rough idle, very little power and once in a while will backfire through throttle body. also while applying steady pressure to gas pedal truck will shake, like it's starvin for gas. if i let off gas it smoothes out or if i mash the gas and go into pass gear it will smooth out. mainly happens at 45mph at 1500 rpm's. cat was replaced about a year ago per the dodge extended warranty and tps also. i have done a full tune up except the coil with all mopar parts. any help is greatly appreciated.

 

its probably the coil, did you replace the fuel filter?

 

no i havent replaced coil cause i thought it would have trown a light if it were bad??? im workin on gettin the fuel pressure tested soon. that should tell me if its a problem in the fuel system, right??

 

a coil wouldnt necessarily throw a code. Mine didnt. the fuel filter is so cheap its worth replacing anyways. If the factory one is still on there at 82K miles it should be replaced anyways.

 

i thought the fuel filter and the pump were one unit? in other words you have to replace the pump and filter all at one time? how do you test a coil?

 

fuel filter should be a metal cylinder along the drivers frame rail. its like $15 at Napa. I dont know how to test an ignition coil. I assume it has one coil for all 6 cylinders. In which case that too is a cheap part. for an hours diagnose time, the dealer can usually pinpoint the problem. Then you can buy the parts and do it yourself for way cheaper.