3.8L engine. Initially getting codes P0301, P0302, P0303 and P0172. Idle is smooth but the van will not go over 40MPH. The engine shakes under load and the check engine light flashes. Plugs and wires are good and I just replaced the coil pack. The van does have a small exhaust leak, but that is not a new thing. MAF is ok. I cleared the codes and drove the van until the engine light came on, now it shows P0300. Any thoughts would greatly be appreciated.
use a scanner and do a cylinder contribution or a misfire counter while you are experiencing the running bad condition. see what cylinders are missing and see what your fuel trims read. Verify that your fuel pressure is 28 - 45 running or 35 - 45 key on engine off with key cycled on.
you could have a fuel problem, a plugged cat, injector problems, dirty MAF, Bad O2 sensor, it all things you will have to check out. you can look at most of the computer inputs and readings with a scanner on the truck