Not sure there are a lot of economical upgrades you can do as this is a "dog" performance vehicle. Any real upgrades would not be cheap, wouldn't be...
Unless you are REALLY having a timing issue, I'd leave it alone. Have to be really careful about it, or it is not going to end well and be more grief...
May be able to find a replacement OEM on EBAY if the original is faulty. Not sure if the original question was for informational purposes or there is...
I'd try the brass bushing (check to see if the old bushing has failed). If it is gone you probably can't go over 25-30 mph or so. Problem is probably...