how many miles? im driving a 2000 dodge rm 1500 van and im having the same problem at 170,000 miles. if im cruising around at 30/40 mph the van runs decent but if i push it hard like up hills or on the highway it misfires and runs really bad sometimes. i had a mechanic back pressure test my van (so he said after keeping it for 4 days) and told me my catalytic converter was clogged. im going to get a gauge and test it myself. there's exhaust coming out of the tailpipe and its not throwing any codes relating to the cat. i know my plenum gasket is leaking in my air intake manifold which may be plugging up the catalytic converter and screwing around with the oxygen sensor, but its not throwing out any codes. im thinking about changing the intake manifold to the huges fi air gap if im taking the manifold off anyway. it has no plenum gasket to go bad at the bottom of the manifold and it bolts right on to the stock 5.2. all said and done i love this van. it has made me money and has always done everything asked of it. im going to try to keep her running forever. i CAN tell you if your going to change any sensors such as the crank position sensor use OEM parts, i cannot stress that enough. i tried to put aftermarket parts on my van and they caused all kinds of problems.