Im sure this is a standard question, but I was unable to find a relevant thread if someone can point me in the right direction. I have a 99 Silverado 5.3L with about 160K miles which seems to have lost A LOT of its power, specifically while towing (21' boat). What is the best course of action, things to check/change/add. All standard maintenance has been kept up including oil, air filter, fuel filter, etc. I was looking at programmers, unfortunately CA legal, but did not want to go this route if there was a mechanical issue that needs to be addressed first. Im on a very limited budget and just trying to explore my options. Thanks for any help.