Hello to everyone i am new to this,, but i have been searchin the web for answers and am hopin that i find it here... I have a 97 150 2 wheel drive,with the 4.6 it has 340,000km runs good till a week ago, my truck started to get poor fuel mileage and idleing ruff ,, So i change the spark plugs , air filter and changed oil but apon starting my truck the oil pressure gauge max out without any warning lights comin on ,, so i changed my oil sending unit and now i have NO oil pressure at the gauge and it idles even worse, the other day i took it for a drive and it stalled when i was turning a corner,, Has anybody had similar problems or know anything that might help me thanks everybody

 

you may not have electrical problem, per-sey. but...checking the alterantor output couldn't hurt, as well as, cleaning the battery posts.

verify with a mechanical oil pressure gauge what is the actual oil pressure...the gauge on the dash...is a glorified indicator. (not real accurate).

the runability can be several things.
1st step is get the codes scanned...& see what is tripped

changing the plugs with that many miles/Km was a good step.
do you have coil packs (2) or do you have individual coils per cylinder??
you may have a faulty coils.

Did you use dielectric grease or compound when installing the new plugs?

might also be wise to remove the throttle body housing and clean it with some carb cleaner... (& the throttle plate) there are 2 EGR ports in there that tend to get plugged/carboned up.

Also remove the IAC...clean it with wd40...making sure the small shaft inside moves freely, let dry and reinstall. this controls the idle. It still maybe neccessary to get a new one ...but many have success cleaning these.

check for vacuum leaks...the elbow on the rear of the throttle body housing is known trouble spot....but check it all over.

have you had the fuel pressure tested?

 

thanks enrinched&beyond ,,, i haven'y checked the alternator yet will be workin on my truck this weekend but to answer sum of your suggestions ,, I cleaned the battery post and put grease on the terminals and also on the plugs when i changed them ,, i used a obd 2 reader and can up zero for any codes, i do have 2 coils on my truck will be checkin those along with the throttle body this weekend and once again thank you very much been alot of help