4.6L GT engine hesitating

[89-5leet-eh]

Hi guys wondered if anyone could help with this problem.Is a 98 GT wth 4.6L auto,It fires up and idles very good and will accelerate just fine up to about 1/4 throttle then engine bigins to hesitate( like a misfire on a cylinder).It seems to me it is a bad plug wire or plug, i have checked plugs they "look" fine and have ordered new wires.Just curious if there is any other possibility that is common or not.I also cleaned the mass air with a spray of carb cleaner and carefully reassembled that.It did sit for 4 years without running and had some old fuel left in the tank,i drained most (90% or so ) and added fresh.Also had to install a new fuel pump it is working fine.I will replace fuel filter soon it just wont come off on the outlet side and will have to have another try at it ..grr.Car has been driven maybe 15 miles /35km or so since i brought it back to life. suggestions-ideas ..TY

 

[COramprat]

Most of it you look like you have or will address but I'd look at injectors too. Since it sat for a while you may have some build-up there.

 

[wmburns]

Cleaning the MAF with choke and carb cleaner most likely damaged it. The sensor is much to fraigle for harsh chemicals. Use only cleaner designed for the purpose.

Monitor LTFT at ldle and under load. Looking for large swings when going from Idle to load.

Besides ignition, other things that can cause hesitation could be water in the spark plug wells, vacuum leak, MAF, bad gas, dirty fuel injectors, excessive EGR flow, clogged cats, low fuel pressure, disconnected fuel pressure vacuum reference.

A possibility to consider is an injector cleaning service such as injectorrx.com. I have used them for 2 sets of injectors with great results.

 

[pilks]

I have a 1998 Mustang GT and my o2 sensors needed to be replaced.. my cel came on but id recommend replacing those too, I only had 37,000 miles on my car, but its also 12 years old, dust, dirt, road salt etc delivers abuse over the years.