Chrysler Repair: chrysler voyager lacks power, chrysler voyager, head gasket

Question
1998 chrysler voyager 2000cc petrol is lacking power, on hills just seems to fade away need to change down to first gear, this is since head gasket replaced and valves done, have checked and rechecked valve timing has had new complete exhaust including cat, has had new fuel filter air filter and plugs, car idles and revs smoothly and emission readings are perfect through the range, car seems to be retarded in my opinion but cannot find anything wrong. would would appreciate any suggestions  you can give me. also would like test data for things like map sensor throttle switch etc. if you could point me in right direction .  many thanks.  rick

Answer
Hi Rick,
I am not familiar with there being a 2.0L engine in a van, but then that may have been one that is sold overseas from the U.S.(?). I have seen it in the cars, but not a van.
I would be inclined to do three things:
Try getting fault codes from the engine controller memory via a code reader plugged into data link plug under the dash. That would be the best way to get data about the sensors as to whether any of them are faulty. You might try to use the ignition key: "on-off-on-off-on and leave on" and then watch for any fault codes that might appear in the odometer window, or watch the check engine light to see if it begins to flash, pause, flash, etc. If that occurs, count the number of flashes before each pause. Group the numbers is pairs to form the two digit fault codes. Write back if you get fault codes one way or the other.
Then compression testing the cylinders would be worthwhile. And finally, fuel pressure tests would be useful too.
You can reach me by the "rate the expert" tab where there is an opportunity to enter text in the "comments" section.
Roland