Oldsmobile/Buick Repair: rough running sillouette, throttle position sensor, crank shaft

Question
hi ED,
My 98 sillouette van has been a pain in my butt.Setting a code saying misfire cyl 4 at local Auto Zone.Had code cleared. So I put new plugs and wires on and still misfire cyl 4.Had code cleared.SO I moved the 3 packs on the module around to see if the misfire would move with a certin pack.After the move problem stopped.A couple weeks later SES light starts to flash again.Took back to A Z same old misfire cyl 4. so had A Z run test on pack module and it tested good. SO bite the big one.Took to local garage and had it hooked up to diagnositc machine $50.00.Tech says "misfire cyl 4 but set 5 other codes:crank shaft sensor,cam shaft sensor,pcm, throttle position sensor,and map".So my ? to you is have you seen this type of problem before and what to do.Wife and 5 kids, i cant be throwing a shitload of parts at it nor afford to take it to the garage$$$$$$$$$$$$$$$$$.
                           Eric  

Answer
Hi,Eric

 Ah yes ive seen this many times,matter of fact we began working on this problem 5000 miles into the first 98 U van {sillouette},what may be going on is first the missfire,this is caused by excessive deposites in the fuel injector,the U van is notorious for having injector problems,GM fix was for us to perform an injector cleaning for 15 min to remove the deposites,only to have it come back 5-10000 miles later for the same problem,we began installing injectors instead of cleaning them,so the option is yours,either clean the injectors good and hope it will work for awhile or just replace them,GM has issued new injectors for the problem and to let you know the injectors have changed part numbers 5 times since then,meaning that they have refined them,if you do go that route and replace them you can do just the #4 injector,but you may end up seeing the same problem with the others.
 Try cleaning them first,that way you can save some money and maybe they will last for awhile.
 As far as the other codes,they were flagged because of the missfire,i doubt they all were true fail codes,meaning there may have been a generic mem reset codes,so i wouldnt worry about those other codes,the main one is the missfire.also on a side note,i have done alot of intake manifold gaskets on the U vans,keep a heads up on that,if your loosing coolant,they are notorious intake leakers,if you need more help let me know.Thanks


ED