1993 f150 5.0 - power loss/shaking

[f150help]

1993 f150 supercab 5.0 4x4 171000 miles: The truck accelerates/drives fine from stop to 20-25 mph - however after this point the truck begins to shake badly and loses power -- the shaking and power loss is more apparent when going up an incline. Whether it's in 4wheel drive or not makes no difference. However, putting the overdrive to "off" on the push button, decreases the shaking and power loss. The shaking is also worse the faster the vehicle is going - or tries to get going. It is as though it is all running pretty good until it hits the last gear and "boom" - the whole vehicle is just bouncing/shaking and the engine loses power --taking the foot off the gas corrects the problem as all symptoms of shaking stop. Vehicle has recently had a full tune up at the shop. Any ideas?? I don't know what the problem is. I'd like to keep it, but I can't if it isn't going to be a vehicle that drives correctly. I have ran several bottles of engin/fuel system cleaner through - no help. I appreciate any ideas or any experience with similar issues. Thanks so much.

[FORDTRACMAN]

Replace fuel filter.Have fuel pressure checked.
Report back

[mustangmike351c]

check the plug wires make sure they are all on tight. then run #7 as far away from #8 as you can. If 7 & 8 are side buy side you could get preignition on #8 it fires 8 at 100 deg btdc.

[andy2005]

My '90 F-150 did the something very similar. I tuned it up and the problem went away, you may also have a vaccuum leak.