First, thank you to all for your ideas on my 3.9 question. We checked all the compression and this motor has over 150 on every cylinder. Replaced all plugs and wires and fired it up. Started up great, went down the road backfiring, coughing, etc. Noticed alot of noise from front of engine, suspect timing chain slop. Is this normal for a 3.9 with 120,000 miles? If I go to Advance Auto Parts and buy a new one will it fix it, I mean the whole timing chain set; gears and chain? No codes have popped up. Pulled PCV and the revs came up, sounded better but the timing probably advanced with the rpm. I thought it was vacuum but everything seems OK. Seems to be timing. Does anyone know the exact steps to set timing on this truck 90 dakota 3.9? Thank you again

 

Ya I would say timing or the plug wires. Check the FAQ for online manual to set the timing.

 

i did mine with a new water pump in about eh 3 hrs the fan clutch was a bitch