Chrysler Repair: 90 Grand Voyager runs rough., voyeger, grand voyager

Question
There are no adjustments on the 90 voyeger. It is running very rough and has loss of power. I have put new Plug Wires, Plugs, Fuel Filter, Run Injector Cleaner and it still runs rough. There is a loss of power. Before it ran rough, a dealer checked codes and everything showed normal. What should I check?  

Answer
Hi John,
It would be good to know if there are any fault codes now, and fortunately you don't have to go to a dealer for that.  Try using the ignition key: turn it "on-off-on-off-on" and leave it "on" (doing this quickly, no longer than 5 seconds). By "on" I mean just the normal position when the engine is running, not the cranking position. The 'check engine' light will remain on when you leave the key in the "on" position with the engine still not running. But then watch the 'check engine' light to begin flashing, then pause, flashing, pause, etc. Count the number of flashes before each pause and keep track of the numbers. Repeat the readout and verify the counts are correct. Then group them in pairs in the order that they came out, thus forming two digit numbers. You may notice that the pause is shorter between the digits of a given number, and longer between the numbers themselves. Then send me a 'follow-up' question telling me the results of your readout. By the way, 55 will be the last number (two groups of 5 flashes each) and that is the code for "end of readout".
I have the troubleshooting manual for several engines and we can look up the possibilities of what is wrong based upon what fault codes you show. When you write back tell me what engine is in the van you are driving.
There is also an essay on fault codes at the site:
http://www.allpar.com/fix/codes.html
which gives the meaning of the code numbers. But then you need to get specific info for what exactly might be the diagnostic tests or parts to replace to complete the repair.
If you also could describe by "rough" more specifically (do you mean 'missing' in regular fashion or is spontaneously speeding and slowing down with no predictable response to the gas pedal; and is it just at idle, at low speed, on the highway at high speed, or a combination of all) that would help. One common problem (when all of a sudden you are going along fine and you need to slow down and the engine begins to buck and idle poorly) is worth considering if you have no fault codes. That is often the first sign of a sticking exhaust gas recirculation (EGR) valve. That can often be easily diagnosed and remedied.
So those are some ideas for you to consider. Let me know what happens with the code readout and we'll go from there.
Roland