hey just read all your post and it does sound like alifter tick i have heard some loud lifters in my day. one thing that u can try is a product called seafoam! they sell it at auto stores and malwart, now i have used this product and done what i am about to tell you to do about 8 times to 8 diffrent cars. ok take your can of seafoam pour half a bottle into your oil "yes your oil" and let your truck run for about 15 mins to get good and warm this will loosen any depostest where ever your oil tocuhs. let your car sit for about 15 more and change your oil with some cheap oil just the cheapest oil you can find because its only going to be in there around 25 to 50 miles, after the 50 miles change your oil to your normail oil rather it be synthetic or a blend or your conventional. just change it at 50 miles. and when you change it after the 50 miles you can watch the blackness pour out. i have seen chunck of sludge fall outta a 2001 grand prix. there was no oil flow to the heads i looked down the oil fill neck and there was nothing. after i did this the oil cap couldnt be taking off the car because it was flowing so great. the car was awsome after this. just a thought it will work to clean your motor up and it is intended to do this just read the can. and follow my directions.
another great thing you can do with the the seafoam is suck it thro a vacum hose will the car is idling. i use the brake booster vacum, just take it off have some one start the car or you start it and pull the hose off, put your finger over the hose theres lots of sucktion there. then very very very very very slowly let the vacum kinda suck the fluid from the tip off the can i put about 6/8 of my finger over the hole and pull about a inch away and start to dump the fluid slowly towards the hole and it will suck it, it should only be a fince stream dooo notttttt let it suckabunch up in there at once it could possibly hydrolock your motor. it would take a lot but just do it slow. after you get your half of other can in there prolly take ten to fifteen mins to do so turn your car off. let it sit for about 15 to 20 mins then fire it up
now let it idle for the first 30 secs then lightly give it some gas get your rpms up to around 3k little presses. then after about a min of that take her for a drive and be normal then get on it a lil not a lot a lil and just watch your 4.0L smoke to high heaven lol. the smoke will stop after a few get home rev her up and fell how much better the accl feels and how much crisper it is. thing will fire up a bit easier also. i like the seafoam alot i was told about it some years ago by a buddy on a forum and wow i just love it. NEVER had a problem with it and it is safe for any motor. check it out
hope this helps it only cost
less than 10 for cheap oil and then a filtter 4.00
new regualar oil 30+??? i dont know what you use my royal purple runs me 60
and a nice new filter fram xg16 i beleave bout 8 bucks
so about 60 bucks but well worth it