96 astro clatter and power loss

[astronomer]

Just bought this van and drove it from north Indiana to Augusta, Ga and back. on the level and down hill ok. uphill 18 wheelers were passing me in the mountains. Also when at the top of each gear just before it shifts a clatter builds in volume and then quits when the next gear takes over. Had the fuel filter replaced in Augusta with no improvement. Changed the cap, rotor, plugs and wires yesterday (in Indiana). While I had the dog house off i revved it up to that rpm range that makes the clatter and it got louder as I increased the rpms and the whole engine started vibrating like something is outa balance. I also "tried" to replace the tps. the old one came right off...the new one would not seat all the way and now is stuck on the shaft. Very frustrated and running out of money and ideas...Any help would be great.

[LaGrasta]

Sorry to hear of the troubles. Know that these engines are easily sorted and usually cost effective. Many of us have 300k+ miles. My suggestions for you, considering what you've already replaced is a valve adjustment.
This is a great site with much help, i'm certain others will chime in with suggestions too. Keep us posted.