feeing a sudden "push" when driving '03 windstar

[archangel777]

Hi people, as u may know, I'm new to this site and I'm happy to be here. Thanx for any and all help received!
My problem is when I start the van in the mornings and start to drive, I notice a sharp and sudden push that feels as if I've been bumped from behind. Its not a big push but its definetely noticable. I just purchased this van about a month ago and I really hope that it isn't a transmission problem. I've tried to read some of the threads here but little help. I read that one person on here changed his tranny but that wasn't the problem. He still feel a "bump" from his van.
I'm not mechanically gifted enough to attempt any serious repairs on my own and these mechanics in Brooklyn, NY are sharks that love people like me who aren't knowledgable about issues like I've described.
Hopefully I can get some insight to this problem before it gets worse.
Thanks in advance for any advice offered

[wiswind]

Of course, like you, the first thing that I think of is the transmission.
Sticking valves in the transmission......Transmission Range Sensor (TRS) aka Neutral Safety Switch can cause abrupt shifts.
A good idea for a "New to me" car (2nd hand) is to change out fluids.
This would start with a fluid exchange for the transmission.
I have a bunch of pictures posted of various projects on my '96 3.8L......which includes a series that show the fluid exchange.
You can also have this done at many oil change shops.....but I would consider taking in my own fluid if not sure of what they are using.
The correct fluid for ALL years of the Windstar is now a fluid that meets the Mercon V specification....... Look for the MERCON V (not just Mercon) on the label.
Mobil 1 make one.....as well as others.
All you want is a fluid exchange....and the filter changed.
I have used AutoRX (only available online).....but would not use ANY other "cleaner" in the transmission.
The AutoRX (9 ounces) is added to the transmission fluid....and 1000 miles later the transmission fluid is changed.
Transmission fluid needs to be changed AT LEAST every 30K miles on the Windstar.....and is a often overlooked maintenance.......which is not good.
If your unit has many miles.....and the fluid has NOT been changed (or you don't know if it has) and fluid exchange, with AutoRX treatment......and a change again in 1000 to 1500 miles might be an idea.
The thought being......replace dirty fluid.......and the new fluid may work deposits loose......which will need to be flushed from the system.
The AutoRX will help to clean up in the valve bodies.
Of course......nothing will repair wear.......but cleaning things up is a good first step.....

I would also exchange the Coolant, motor oil, and the power steering fluid.
The Power Steering uses Automatic Transmission fluid.......NOT "power steering fluid".

Other things to consider would be normal tune-up items like the fuel filter, spark plugs, spark plug wires and fuel system cleaner (Berryman's B-12 Chemtool).

Getting all the routine maintenance items taken care of may solve the problem....and are things that just should be done anyhow.
I don't want to see you troubleshoot a problem.....replacing things.....only to find out that routine mainenance would have solved the issue.

Oh....don't be scared off by all the projects that I have done......Mine is a '96 that I bought with just under 38K miles on it in '99. Now has over 208K miles on it......and mechanically is in very good condition.

[tripletdaddy]

Does it seem like it is sluggish? Can you tell if the engine is doing great, not sounding weak but the trans seems ok but then takes off with this surge? Just to be thorough, have you checked the trans fluid for color - bright cherry red, smell - not burnt or bitter, and correct amount - between full marks after fully warmed up, several mile drive, all gears, parked running on a level spot. Since you mentioned someone else had a similar problem, changed the trans and still has the problem, that make me want to look at the engine. Does it sound like it's really the trans picking up speed or the engine? If you have a tach does the tach needle jump when it surges? If so, this is an engine problem. The tach would jump if the trans slipped, but instead you are saying the van briefly accelerates. Does it do this between gear changes or when it's changing gears or only after in the last gear? Does it do it in reverse? Does it act like it can't make up its mind which gear it should be in? Perhaps you just need a tune up and a throttle body, mass air flow, IAC and EGR port cleaning. Could have a myriad of sensors not right. Have you had it checked for any codes that may be stored if the CEL has not come on?